Mn hc

PHN TCH V THIT K H THNG THNG TIN(4 VHT + 1 bi tp ln) Kin thc chun b: + C s d liu + Ngn ng lp trnh Mc ch mn hc: + Gii thiu v phng php PTTK HT c cu trc + C th phng php lun PTTK c cu trc + Gii thiu cc cng c phn tch + Cch thit k mt h thng. Cch tip cn: TopDown Ni dung gm: Chng 1: i cng v cc h thng thng tin qun l Chng 2: Kho st hin trng v xc lp d n Chng 3: Phng php lun phn tch v thit k h thng Chng 4: Phn tch h thng v x l Chng 5: Phn tch h thng v d liu Chng 6: Thit k h thng Ti liu tham kho: 1. Nguyn Vn Ba. Phn tch thit k HTTT - NXB HQG H Ni 3. Thc Bnh Cng. Phn tch thit k HTTT NXB Khoa hc v k thut 4. inh Th Hin. Phn tch thit k HTTT NXB Thng k

5. Ng Trung Vit, Phn tch v thit k h thng qun l- kinh doanh nghip v, nxb Giao thng Vn ti 6. L Tin Vng, Nhp mn CSDL quan h 7. Nguyn B Tng, C s d liu l thuyt v thc hnh, Nxb HQG

2

Mc lc Mc lc.............................................................................................3 Chng I i cng v cc h thng thng tin trong qun l..........................6 1. Khi nim v h thng..............................................................6 1.1. H thng.............................................................................6 1.2. Mi trng ca h thng.....................................................7 2. H thng kinh doanh.................................................................7 2.1. H thng kinh doanh...........................................................7 2.2. c im ca h thng KD..................................................8 2.3. Cc thnh phn ca h thng KD........................................8 3. H thng thng tin qun l........................................................8 3.1. Khi nim qun l...............................................................9 3.2. Chc nng ca h thng thng tin qun l..........................9 3.3. Nhim v ca h thng thng tin........................................9 3.4. Vng i ca h thng thng tin.......................................10 3.4. Cc b phn hp thnh ca H thng thng tin................11 4. Cc h thng thng tin t ng ho (tin hc ho)...................11 4.1. Mc t ng ho..........................................................11 4.2. Cc phng thc x l bng my tnh...............................12 5. Cc giai on phn tch v thit k H thng thng tin...........12 5.1. Gii thiu...........................................................................12 5.2. Cc giai on phn tch thit k h thng thng tin theo phng php SADT (k thut phn tch v thit k c cu trc) ................................................................................................12 Chng II Kho st hin trng v xc lp d n.............................................15 1. Mc ch, yu cu ca vic kho st.......................................16 2. Kho st v nh gi hin trng..............................................16 2.1. Ni dung kho st v nh gi hin trng.........................16 2.2. Cc mc kho st..............................................................16 2.3. Cc hnh thc tin hnh kho st......................................17 2.4. Phn loi v h thng ho thng tin thu thp c ..........17 2.5. Pht hin nhng yu km ca hin trng v nhng yu cu trong tng lai.........................................................................18 3. Xc nh phm vi, kh nng v mc tiu ca d n................18 3.1. Xc nh phm vi (khoanh vng d n).............................18 3.2. Kh nng v hn ch thc hin d n...............................19 3.3. Mc tiu ca vic tin hc ho............................................19 3.4. Xc nh yu t thnh cng ca bi ton..........................19 4. Phc ho gii php, cn nhc tnh kh thi...............................19 4.1. Cc mc t ng ho........................................................193

4.2. Hnh thc s dng my tnh.............................................19 4.3. Phn tch hiu qu v nh gi tnh kh thi......................19 5. Lp d tr v k hoch trin khai d n..................................20 5.1. Hnh thnh hp ng.........................................................20 2. Lp d tr thit b................................................................20 3. Lp k hoch trin khai d n..............................................20 Chng 3: Phng php lun phn tch thit k h thng c cu trc .......................................................................................................21 1. Cch tip cn tin hc ho: 2 cch............................................23 2. Phn tch thit k h thng c phng php...........................24 3. Phng php lun phn tch thit k h thng c cu trc......24 4. Cc phin bn khc nhau ca phng php lun phn tch c cu trc.......................................................................................25 5. T chc xy dng h thng thng tin......................................25 Chng 4: Phn tch h thng v x l...........................................26 1. Mc ch, yu cu ca giai on phn tch..............................27 1.1. Mc ch............................................................................27 1.2. Cch tin hnh..................................................................27 2. Biu phn cp chc nng (BPC - Bussiness Function Diagram).....................................................................................27 2.1. Khi nim..........................................................................27 2.2. Cc thnh phn ca BPC...................................................27 2.3. c im ca biu phn cp chc nng.......................28 2.4. Cch xy dng BPC...........................................................29 3. Biu lung d liu (BLD - Data Flow Diagram)....................30 3.1. Gii thiu v BLD...............................................................30 3.2 Biu lung d liu mc vt l (Hay cc lu h thng) ................................................................................................30 3.3 Biu lung d liu (BLD- Data Flow Diagram)................33 3.4. Chuyn t BLD mc vt l sang mc logic........................45 Chng 5: Phn tch h thng v d liu.......................................49 1. Mc ch, yu cu ca vic phn tch d liu..........................49 1.1. Mc ch ca giai on......................................................49 1.2. Yu cu.............................................................................49 1.3. Phng php thc hin: C 2 phng php tip cn:........49 2. Biu cu trc d liu theo m hnh thc th lin kt (ER entity relation )...........................................................................49 2.1. S thc th ..................................................................49 2.2. Cc thnh phn ca s thc th...................................49 2.3. Xy dng s thc th - lin kt.....................................53 3. Hai cch tip cn thit k c s d liu quan h.................56 3.1. Chun ho theo hng phn tch:.....................................56 3.2. Chun ho theo hng tng hp:......................................57 5. Xc nh mi quan h xy dng s E-R.............................604

6. M ho cc tn gi:.................................................................64 6.1. Khi nim m ho.............................................................64 6.2. Cht lng c bn ca m ho..........................................64 6.3. Cc kiu m ho khc nhau..............................................65 7. T in d liu........................................................................67 7.1. Khi nim:.........................................................................67 7.2. Cc hnh thc thc hin t in:........................................68 7.3. Cu to t in:................................................................68 Chng 6: Thit k h thng..........................................................70 1. Thit k tng th.....................................................................70 1.1. Phn nh ranh gii gia chc nng my tnh v chc nng th cng...................................................................................70 1.2. Phn nh cc h thng con ca my tnh.........................71 2. Thit k chi tit v cc th tc th cng v v cc giao tip ngi - my.................................................................................72 2.1. Cc chc nng th cng....................................................72 2.2. Thit k u vo ca thng tin..........................................73 2.4. Thit k mn hnh chn.....................................................74 3. Thit k chng trnh..............................................................74 3.1.i cng...........................................................................74 3.2. Cc m un chng trnh..................................................75 3.3. Lc cu trc................................................................75 3.4. nh gi v lc cu trc.............................................76 3.5. Chuyn BLD thnh LCT......................................................77 4. Thit k c s d liu..............................................................78 4. 1. Mc ch...........................................................................78 4.2. Thnh lp lc logic.....................................................79 4.2.5. Nguyn tc truy nhp.....................................................83 4.3. Thnh lp lc vt l....................................................84 5. Thit k kim sot...................................................................85 5.1. Gii thiu...........................................................................85 5.2. Nghin cu kim tra thng tin nhp, xut.........................85 5.3. Nghin cu cc giai on tip cn phn tch cc kim sot ................................................................................................86 5.4. Nghin cu cc kh nng gin on chng trnh v phc hi............................................................................................87 6. Lp trnh, chy th v bo tr..................................................89 6.1. Lp trnh............................................................................89 6.2. Vit ti liu hng dn s dng.........................................89 6.3. Bo tr h thng................................................................90

5

Chng I i cng v cc h thng thng tin trong qun l1. Khi nim v h thng 1.1. H thng nh ngha: H thng l tp hp gm nhiu phn t c cc mi quan h rng buc ln nhau v cng hot ng hng ti mt mc ch chung. (v d mt c my l mt h thng cc chi tit lin kt vi nhau thc hin chc nng ca c my...). Nghin cu h thng l nghin cu xem h thng bin i ci g, bin i nh th no? Ci vo Ci vo Ci ra H thng Ci ra Ci vo Ci ra

Bin i

Nhng yu t c bn ca mt h thng bao gm:- H thng lun c mc tiu, phi hng v mt mc ch chung - Phn t trong h thng bao gm cc phng tin, vt cht v nhn lc, mi phn t u c thuc tnh c trng quyt nh vai tr ca n trong h thng. - H thng c gii hn xc nh nhng phn t trong v ngoi h thng, tnh gii hn mang tnh cht m. Trong mt h thng cn c th c nhng h thng con. - Gia cc phn t lun c mi quan h, mi quan h ny c th l bn cht vt l hoc thng tin, cc mi quan h quyt nh s tn ti v pht trin ca h thng. Mi khi thm bt phn t s lm bin i cc mi quan h.6

- H thng c tnh kim sot (cn bng v t iu chnh) iu m bo tnh thng nht, n nh v theo ui mc tiu ca mnh. - H thng nm trong mt mi trng, trong c mt s phn t ca h tng tc vi mi trng bn ngoi. phn bit mi trng vi h thng ta cn phi xc nh gii hn ca h thng v phng din vt l hay khi nim, chnh xc ho cc giao im ca mi trng v h thng 1.2. Mi trng ca h thng Mi trng ca h thng l tp hp cc phn t khng thuc v h thng nhng trao i thng tin vi h thng. Vic xc nh mi trng (hay cn gi l khoanh vng h thng) da trn mc tiu c bn trn ton h thng.Mi trng

H thng

Hnh 1 mi trng v h thng VD: S quan h gia X nghip v mi trng (H.2)NH CUNG CPNVL, dch v hng ho Dch v ti chnh NVL, dch v hng ho Dch v ti chnh

NGN HNG NVL, dch v hng ho Dch v ti chnhDng thanh ton

X NGHIPSn phm

KHCH HNG

I L

2. H thng kinh doanh Hnh 2 v d v mt h thng 2.1. H thng kinh doanh L khi nim chung dng cho cc t chc kinh t nh nh my, x nghip, cng ty, t chc dch v... c mc ch phc v cho kinh doanh (business). Kinh doanh c th v li ch hoc v li nhun. V d: - Cc cng ty, nh my, dch v ... l cc h thng kinh doanh v li nhun

7

- Cc trng hc, cc cng trnh cng cng, bnh vin, ... l cc h thng kinh doanh v li ch. 2.2. c im ca h thng KD - C s tham gia ca con ngi, c s sng to bng tr tu con ngi, lun bin ng cnh tranh khng ngng v s lng v cht lng - Mc ch ca h thng ny do con ngi t ra v phc v con ngi 2.3. Cc thnh phn ca h thng KD

H quyt nh: H quyt nh gm con ngi, phng tin, phng php xut cc quyt nh, cc chin lc kinh doanh, n c lin quan n mi hot ng ca ton h thng. Qu trnh ra mt quyt nh tri qua hai bc: -Tm hiu tnh hnh -La chn gii php

Tu theo tm quan trng, phm vi nh hng ta chia lm 2 loi quyt nh: - Quyt nh chin lc: L quyt nh cho mt k hoch tng th lu di, c tnh cht nh hng - Quyt nh chin thut: Quyt nh ny c tnh cht cc b c phm vi hp trong thi gian ngn h tr cho quyt nh chin lc

H tc nghip: H tc nghip bao gm con ngi, phng tin trc tip thc hin cc nhim v ca h thng kinh doanh t mc tiu xc nh. H thng thng tin: Bao gm con ngi, phng tin v phng php tham gia vo qu trnh thu thp, lu tr, x l thng tin m bo mi quan h gia h quyt nh v h tc nghip. -Nhng thng phn nh tnh trng hin thi ca h thng (tnh trng kinh doanh, thng tin v vt t, thit b, nhn s... -Nhng thng tin vo, ra

Thng tin bao gm:

H Q

VoH thng

Rathng tin H tc nghip

3. H thng thng tin Hnh 3lcu trc ca h thng KD qun8

3.1. Khi nim qun l - Cng tc qun l: - Qun l nh mt qu trnh bin i thng tin a n hnh ng, l mt qu trnh tng ng vic ra quyt nh. (J.W.Forsester) - Qun l bao gm vic iu ho cc ngun ti nguyn (nhn lc v vt cht) t ti mc ch... (F.Kasat v J.Rosenweig). - Cng tc qun l l mt ngh thut ng x ring ca tng c nhn lnh o tu thuc vo hon cnh kinh t x hi, tnh a dng ca mi trng l mt ngh thut t c mt mc ch no thng qua mt s ngi no . - Tri thc qun l: L kinh nghim thc t kt hp vi kt qu nghin cu khoa hc ca nhiu ngnh trong ngh ch quan ng vai tr quan trng. - Cc t c bn cu cng tc qun l:- Hng ti mc ch - Thng qua con ngi - S dng cc k thut - Bn trong mt t chc - Cc chc nng qun l: -Vch k hoch -T chc thc hin -B tr cn b -Lnh o -Kim sot 3.2. Chc nng ca h thng thng tin qun l - H thng thng tin phi h tr cho cc nh qun l h c th a ra nhng sch lc, chin lc trong vic ch o. - Thng tin phi mm do thch ng c vi nhng thay i v nhu cu v thng tin bng cch iu chnh nhng kh nng x l ca h thng. - Nhu cu thng tin cc mc qun l khc nhau:Phn tch xu hng K hoch, iu chnh Bo co nh k X l giao dch C. lc Sch lc Tc nghip Tha hnh

Hnh 4 Cc mc nhu cu thng tin

3.3. Nhim v ca h thng thng tin - i ngoi: Trao i thng tin vi mi trng bn ngoi9

- i ni: HTTT l cu ni lin lc gia cc b phn ca h thng kinh doanh. N cung cp cho b phn quyt nh v b phn tc nghip cc thng tin phn nh tnh trng ni b ca c quan, t chc trong h thng v tnh trng hot ng kinh doanh ca h thng. 3.4. Vng i ca h thng thng tinGiai on Hnh thnh Giai on Pht trin

Giai on Thoi ho

Giai on Khai thc

Hhnh 5

Vng i ca h thng thng tin

- Giai on hnh thnh: Mt ai c tng v h thng thng tin c th gip cung cp thng tin c tt hn. - Giai on pht trin: tng tr thnh thc t, nh phn tch h thng, ngi lp trnh v ngi s dng cng lm vic vi nhau phn tch cc nhu cu x l thng tin v thit k ra h thng thng tin. c t thit k c chuyn thnh cc chng trnh v h thng c ci t. - Giai on khai thc: Sau khi ci t, h thng tin bc vo giai on sn xut v i vo vn hnh bnh thng phc v cho nhu cu thng tin ca cng ty. Giai on khai thc l giai on di nht trong c 4 giai on (thng ko di t 4-7 nm). Trong giai on ny h thng tin lin tc c sa i hoc bo tr gi n thay i cng vi nhu cu ca cng ty. - Giai on thoi ho: Vic tch lu nhng thng tin bin i, tng trng lm nh hng n tnh hiu qu ca h thng. H thng thng tin tr thnh rc ri n mc khng th bo tr c na, vic duy tr n khng cn kinh t v hiu qu na. Lc ny n s b loi b v chm dt vng i h thng ta phi xy dng h thng mi. Tuy vy, c th mt s m un c ti s dng trong h thng mi. Vic xc nh vng i h thng dn ti vic cn a c yu t loi b h thng vo ngay trong qu trnh pht trin h thng.

10

3.4. Cc b phn hp thnh ca H thng thng tin Nu khng k n con ngi, phng tin th HTTT ch gm 2 b phn l: cc d liu & cc x l - Cc d liu: D liu v cu trc: L nhng s kin, qu trnh tin ho, tng trng, cp nht c lu tr tng i n nh. D liu kinh doanh: Nhng thng tin v hot ng giao dch, thng l nhng tp d liu c cu trc (ho n chng t). Thng tin c cu trc bao gm lung thng tin vo v lung thng tin ra: Lung thng tin vo: phn loi cc thng tin cn x l thnh 3 loi: + Thng tin cn cho tra cu: Cc thng tin t b thay i, thng c cp nht 1 ln. + Thng tin lun chuyn chi tit: l loi thng tin hot ng ca n v, khi lng thng tin thng ln, cn phi x l kp thi + Thng tin lun chuyn tng hp: l loi thng tin c tng hp t cc cp thp hn, thng tin ny thng c ng x l theo k hay theo l Lung thng tin ra: + Thng tin u ra c tng hp t thng tin u vo, ph thuc vo nhu cu qun l trong tng trng hp c th, tng n v c th. + Thng tin u ra quan trng nht l cc tng hp, thng k, thng bo. - Cc x l: - L cc chc nng, quy trnh, phng php, th tc x l cho php thu thp, lu tr, tm kim, ch bin thng tin, thc cht l bin i t tp thng tin vo thnh tp thng tin ra - Cc chc nng x l trong h thng c tnh lin hon vi nhau trong m bo s thng nht, an ton trnh s c 4. Cc h thng thng tin t ng ho (tin hc ho) 4.1. Mc t ng ho H thng t ng ho c th theo hnh thc: - T ng ho ton b: H thng c x l hon ton t ng bng my tnh trong con ngi ch ng vai tr ph trong h thng. - T ng ho mt phn (b phn): H thng c chia thnh hai phn cng vic phn x l gia con ngi (thc hin th cng) v phn thc hin trn my tnh (khng tnh nhng cng vic con ngi phc v my tnh. Vic t ng ho mt h thng kinh doanh c th lm vi hai cch: - Phng php "h": S dng my tnh tp trung bao trm ton b h thng

11

- Phng php "ging": p dng my tnh cho tng b phn ring r, cho tng phm vi nht nh. Tin hc ho ton b l mc ch cui cng nhng khng phi bao gi cng thc hin c, m nhiu khi ngi ta phi tin hnh tin hc ho b phn trc. 4.2. Cc phng thc x l bng my tnh - X l theo l (batch processing): thng dng trong cc trng hp sau: - X l c tnh cht nh k, (in cc bo co, kt xut, thng k) - Trong trng hp in cc giy t c s lng ln - X l trc tuyn (on-line processing): Cc giao dch pht sinh, cc thng tin n c cp nht v cn t ng x l ngay. Th d: Bn v my bay, v tu, cung cp thng tin trn INTERNET... +u im ca x l trc tuyn: - Gim c cng vic giy t, cc khu trung gian - Kim tra c s ng n ca d liu ngay sau khi nhp - Cho tr li nhanh chng +Nhc im: - Xy dng h thng tn cng sc, thi gian, chi ph t hn c v phn cng v phn mm - X l khng kp khi khi lng thng tin vo ra ln - D b nhm ln. - Kh phc hi d liu (v d liu lun trn dng d liu) Thng thng mt h thng c c hai ch x l trn v c s iu khin chuyn i gia hai phng thc thc hin ph hp vi yu cu tr li thng tin. 5. Cc giai on phn tch v thit k H thng thng tin 5.1. Gii thiu Phn tch v thit k mt h thng l vn nhn thc mt h thng. phn tch, thit k ta phi dng cc phng php m t. C nhiu phng php nhng Vit Nam s dng ch yu hai phng php: - SADT (Structure Analysis and Design Technology) - MERI (ca Php) 5.2. Cc giai on phn tch thit k h thng thng tin theo phng php SADT (k thut phn tch v thit k c cu trc)

12

How?

M t h thng thc lm vic nh th no?

Xc nh h thng mi thc hin nh th no?

Mc vt l Mc khi nim hiu h thng lm g? Xc nh h thng mi lm g? Cn ci tin g?

What?

- Giai on 1 xc nh vn c bn v tnh kh thi ca d n: Cn tr li cc cu hi nh: C nn thc hin khng?; Mc chi ph bao nhiu?; Quy m n u?...Cn a ra cc lp lun lm xut hin mc tiu ca n cui cng nu chp nhn d n th phi vch k hoch cho giai on 2. - Giai on 2 phn tch h thng: Giai on ny ta m t h thng mc khi nim phn tch su sc hn cc chc nng, d liu ca h thng c (tr li cc cu hi l g?; lm g?) sau a ra m t khi nim cho h thng mi.. Khi phn tch dng cc biu (chc nng nghip v, lung d liu, m hnh d liu) - Giai on 3 thit k i th: Trn c s m hnh khi nim G 2 ta m t h thng mc vt l, tr li cc cu hi lm th no? Xc nh cc h thng con, vai tr ca my tnh... - Giai on 4 thit k chi tit bao gm: -Thit k c s d liu -Thit k cc th tc, cc m un x l -Thit k cc chc nng chng trnh -Thit k cc mu th KHO ST -Thit k giao din -Thit k cc kim sot - Giai on 5 ci t chng trnh - Giai on 6 khai thc v bo trBO TR V PHT TRIN PHN TCH

Ch : Vic phn chia giai on trn ch c tnh cht tng i. nh gi tng quan gia cc phn cng vic c th c nhiu tiu chun khc nhau tu theo trnh tin hc tng quc THIT K CI T gia. VD: cc nc phng Ty phn cng vic t giai on 1 - 4 c nh gi t 50-60%, phn lp trnh ci t t 20-30%, cn li l phn bo tr.XY DNG

13 Hnh 6 S th hin cc giai on trin khai xy dng mt d n

Cu hi chng 1 1/ Ti sao khi xy dng cc HTTT cn phi c phn tch thit k h thng? 2/ Mc ch ca phn tch thit k h thng? 3/ Nhim v ca HTTT 4/ Vai tr ca HTTT trong h thng kinh doanh? 5/ Cc giai on ca qu trnh PTTK h thng? 6/ Nhng lnh vc no x l theo l, trc tuyn?

14

Chng II Kho st hin trng v xc lp d nTin trnh trin khai mt d n y l giai on u tin ca qu trnh phn tch v thit k h thng, n quyt nh d n c tn ti hay khng. Cc bc tin hnh tng qut nh sau:

Kho st hin trng v thu thp thng tin(Kho st 4 mc: Tha hnh, qun l, lnh o, chuyn gia)

Pht hin yu km v yu cu t ra cho tng lai

Xc nh mc tiu d n (cc b, ton b)

nh gi kh nng thc hin(con ngi, ti chnh, thit b, thi gian, khng gian, mi trng)

Cn nhc tnh kh thi v la chn gii php

Lp d tr v trin khai d n

Cho php gii p mt s cu hi c bn sau: + Mi trng, hon cnh, cc rng buc v hn ch i vi h thng nh th no? + Chc nng v nhim v v mc tiu cn t c ca h thng l g, tc l ngi dng mun g h thng ? + C th hnh dung s b mt gii php c th p ng c cc yu cu t ra nh th no?

15

1. Mc ch, yu cu ca vic kho st Mc ch: Kho st hin trng v xc lp d n l giai on u ca qu trnh phn tch v thit k h thng. Mc ch ca giai on ny l tm c s m t h thng bng vn bn, xut ra phng n thc hin, cui cng l k c mt hp ng v hnh thnh 1 d n mang tnh kh thi (giai on kho st cn c th coi nh "Nghin cu tnh kh thi" hoc "Nghin cu hin trng") Vic kho st thng c tin hnh qua 2 giai on: - Kho st s b nhm xc nh tnh kh thi ca d n. - Kho st chi tit nhm xc nh chnh xc nhng g s thc hin v khng nh nhng li ch km theo Cc yu ca vic kho st: - Kho st, tm hiu, nh gi s hot ng ca h thng c - xut cc yu cu, cc mc tiu v cc u tin gii quyt cho h thng mi. - Phc ho gii php mi v cn nhc tnh kh thi ca d n - Lp k hoch cho d n cng vi cc d tr tng qut. 2. Kho st v nh gi hin trng 2.1. Ni dung kho st v nh gi hin trng - Tm hiu mi trng XH, kinh t, k thut ca h thng, nghin cu c cu t chc ca c quan - Nghin cu chc trch, nhim v, cc trung tm ra quyt nh v iu hnh, s phn cp cc quyn hn - Thu thp, nghin cu cc h s, s sch, cc tp cng vi cc phng thc x l thng tin trong - Thu thp v nghin cu cc qui tc qun l, cc qui nh, cc cng thc lm cn c cho qu trnh x l thng tin - Thu thp cc chng t giao dch v m t cc chu trnh lu chuyn v x l thng tin v ti liu giao dch - Thng k cc phng tin v ti nguyn v c th s dng - Thu thp cc i hi v thng tin, cc kin, d on, nguyn vng trong tng lai nh gi ph phn hin trng, ra hng gii quyt - Lp s tng th v hin trng 2.2. Cc mc kho st Vic tin hnh kho st c tin hnh trn 4 mc i tng

16

- Thao tc tha hnh: l kho st nhng ngi trc tip vi nhng thao tc ca h thng. H c k nng, nghip v cao, nhn bit c nhng kh khn, phc tp v nhiu vn chuyn su trong cng vic. - iu phi qun l: y l nhng ngi qun l trc tip v mt mng cng vic no , chng hn qun c phn xng, h hiu c tnh hnh c quan thi im hin ti nhng khng c kh nng nhn nhn c cc vn xy ra trong tng lai - Quyt nh ca lnh o: y l nhng ngi ra quyt nh nn h c yu cu v cc thng tin tr gip - Mc chuyn gia c vn: y l nhng ngi nhn thc c s pht trin v vn ng ca h thng trong nhng mi trng 2.3. Cc hnh thc tin hnh kho st C nhiu hnh thc kho st, chng c s dng kt hp nng cao hiu qu, tnh xc thc, tnh khch quan, tnh ton din ca vic kho st. (1)- Quan st, theo di, ghi chp (gm quan st chnh thc v khng chnh thc): - Chnh thc: C chun b, c thng bo trc cho i tc chun b thng tin tr li theo yu cu ca ngi kho st. - Khng chnh thc: Khng thng bo trc cho i tc chun b thc hin bt k lc no, u...Vi quan st khng chnh thc thng cho kt lun chnh xc hn, tuy vy cch ny rt mt thi gian, thng lm vic vi nhng ngi lm vic lu din t cho mnh. (2)- Phng vn: a ra nhiu loi cu hi, cu hi trc tip, cu hi ng (lit k tt c cc phng n tr li theo kiu trc nghim), cu hi m c tnh cht gi . (3)- Nghin cu ti liu, cc ti liu gm: - Cc bo co nghip v - Qui ch v chc nng, nhim v - Quy nh, ni qui - Cc s sch thng tin chi tit giao dch hng ngy... (4)- Dng bng hi, phiu iu tra: Gi phiu iu tra cho i tc thu thp tr li x l gin tip khng c s trao i tranh lun. Phng php ny thng nhanh, r tin nhng tin cy thp. 2.4. Phn loi v h thng ho thng tin thu thp c -Thng tin hin ti phn nh chung v mi trng, hon cnh, cc thng s c li ch cho vic tm hiu, nghin cu h thng trong qu kh v hin ti. - Thng tin cho tng lai phi c kho st t m v cht ch. Nhng thng tin ny bao gm nhng thng tin c pht biu ra chng hn nhng li ca thn, phn nn, mong mun, c loi thng tin c thc nhng khng c pht biu ra, trng hp ny phi gi ly c li pht biu chnh thc, c nhng thng tin v thc, y l nhng pht biu khng r rng, mp m, cn phi d on nhn c nhng thng tin .17

- Thng tin tnh (c th cc thng tin s ng, cu trc ho): Nh h s cc phng ban, c nhn (h tn, chc v, nm sinh). - Thng tin ng: Hnh trnh ca thng tin trong h thng. ng v thi gian l thi im thay i, x l, kim tra thng tin. ng v khng gian l con ng di chuyn thng tin trong h thng. - Thng tin bin i: Cc qui tc qun l, quy nh ca Nh nc, ca c quan lm nn cho vic tnh ton, x l, kt xut thng tin. - Thng tin mi trng v thng tin ni b. Thng tin mi trng phn bit c u l phn t trong h thng, u l phn t ngoi h thng. D thng tin v mi trng khng lin quan n h thng nhng c nh hng ln n h thng ta khng th b qua khng xem xt k - Xem xt s b cc thng tin nhn c trn 4 kha cnh sau: - S lng - Tn sut s dng - chnh xc - Thi gian sng 2.5. Pht hin nhng yu km ca hin trng v nhng yu cu trong tng lai + Yu km - Hthng thiu ci g, (chc nng, phng tin, nhn lc) - Km hiu qu, hiu sut cng vic thp - Phng php x l khng cht ch, di chuyn thng tin vng vo - C cu t chc bt hp l - Giy t, ti liu trnh by km gy n tc lm cho h thng qu ti, gy tn ph v vt t, thit b, con ngi + Yu cu ny sinh - Khc phc nhng yu km trn - Nhng yu cu v thng tin cha c p ng - Nhng nguyn vng ca nhn vin - Cc d kin v cc k hoch pht trin v quy m ca n v 3. Xc nh phm vi, kh nng v mc tiu ca d n 3.1. Xc nh phm vi (khoanh vng d n)

- Ch r h thng mi tin hnh trong phm vi no?+ Trong ton b c quan (phng php h) + Trong tng b phn (phng php ging). Nn kho st tng th trc khi khoanh vng ni thc hin tin hc ho. - nh gi tng phng php: + u im ca phng php h l nht qun trong x l, c s d liu tp trung nn trnh c d tha d liu, tuy nhin tc x l s chm, ci t phc tp18

+ Vi phng php ging th d thc hin nhng kh pht trin h thng con thnh h thng tng th. Ch : Mt HTTT thng kh phc tp m khng th thc hin trong mt thi gian nht nh bi vy cn hn ch mt s rng buc h thng mang tnh kh thi nht nh. Ti thi im ny cn xc nh cc mc tiu cho d n, chnh cc mc tiu ny l thc o kim chng v nghim thu d n sau ny. 3.2. Kh nng v hn ch thc hin d n Xt trn 5 mt sau: - V mt ti chnh: Kinh ph cho php trin khai. - V con ngi: Kh nng qun l, nm bt k thut mi, kh nng v o to, tip nhn cng ngh mi - V trang thit b k thut cho php - V mt thi gian: Cc rng buc ca cc h thng v thi gian hon thnh. - V mi trng: Cc yu t nh hng v mi trng, x hi. 3.3. Mc tiu ca vic tin hc ho - Khc phc yu km h thng c - p ng c yu cu trong tng lai - Mang li li ch kinh t - Tho mn c hn ch v chi ph v con ngi - Th hin c chin lc pht trin lu di 3.4. Xc nh yu t thnh cng ca bi ton - Mc tiu qun l: c ch ra bng cm danh ng t th hin tm tt cc qui trnh qun l c bn - Yu t thnh cng ca bi ton (CSF Critical Successful Factor): c th hin bng mt danh t, y l cc thng tin u ra phi c mt ca h thng. 4. Phc ho gii php, cn nhc tnh kh thi 4.1. Cc mc t ng ho - T chc li cc cng vic th cng - T ng ho vic x l tin nhng khng lm thay i c cu t chc - T ng ho km theo thay i t chc 4.2. Hnh thc s dng my tnh - X l theo m hay trc tuyn (offline or online) - X l tp trung/phn tn 4.3. Phn tch hiu qu v nh gi tnh kh thi -Tnh hiu qu: + Chi ph + Li ch (v kinh t) - Tnh kh thi: + Kh thi v mt k thut19

+ Kh thi v tc v + Kh thi v chi ph Nguyn tc chung l xut 1 s phng n i snh 5. Lp d tr v k hoch trin khai d n 5.1. Hnh thnh hp ng Quyt nh h thng kh thi hay khng v tho thun cc iu khon s b dn n 1 hp ng kinh t v trch nhim ca cc bn tham gia. 2. Lp d tr thit b - S b v d n + Khi lng d liu cn lu tr + Cc dng lm vic: Trc tuyn, t xa, theo m,... + S lng ngi dng + Khi lng thng tin cn thu thp, xut ra - Thit b cn c: My tinh n l hay mng my tnh, cc thit b chuyn dng v cc phn mm ang dng... - iu kin mua bn v lp t: iu kin v mt ti chnh, iu kin giao hng, k hoch tp hun, k hoch lp t, o to ngi dng... 3. Lp k hoch trin khai d n - Lp h s k hoch gm: Danh sch thnh vin nhm lm vic gm c hai bn; cc kt qu kho st s b; cc ph phn hin trng v yu cu pht trin trong tng lai; cc gii php v la chn; k hoch trin khai d n. - Thng qua trao i tho lun hon tt cc h s trn. Sau khi quyt nh phn cng nhim v cho tng nhm hay tng c nhn thc hin cc giai on tip theo.

20

Chng 3: Phng php lun phn tch thit k h thng c cu trcNi dung: + Phn loi h thng tin hc / Cch tip cn trong vic tin hc ho + Phng php phn tch thit k h thng + Phng php lun phn tch thit k h thng + T chc xy dng h thng Gii thiu s lc mt s phng php phn tch thit k Phn tch thit k HTTT l phng php lun xy dng v pht trin HTTT bao gm cc l thuyt, m hnh, phng php v cc cng c s dng trong qu trnh phn tch v thit k h thng. C nhiu phng php khc nhau. Phng php SADT (Structured Analysis and Design Technique) K thut phn tch v thit k cu trc Phng php ny xut pht t M, tng c bn ca n: Phn r mt h thng ln thnh cc phn h nh v n gin. - c xy dng da trn 7 nguyn l sau: 1. S dng 1 m hnh 2. Phn tch i xung (top down) 3. Dng mt m hnh chc nng v mt m hnh quan nim (gi l m hnh thit k) 4. Th hin tnh i ngu ca h thng 5. S dng cc biu din di dng ho 6. Phi hp hot ng ca nhm 7. u tin tuyt i cho s vit - SADT s dng cc k thut: + Dng d liu hay cn gi l biu lung d liu (Data Flow Diagrams) + T in d liu (Data Dictionary) + Ting anh c cu trc (Structured English) + Bng quyt nh + Cy quyt nh

Phng php MERISE (Methode pour Rassembler les Idees Sans Effort)21

Phng php MERISE l phng php phn tch c ngun gc t Php, ra i vo cui thp nin 70. - tng c bn xut pht t 3 mt c bn sau: + Mt th nht: Quan tm n chu k sng ca h thng thng tin tri qua nhiu giai on Thai ngn- Quan nim / nim Qun tr Cht, c th ko di t 10 15 nm vi cc t chc ln. + Mt th hai: cp ti chu k c t hay chu k tru tng. Qui trnh x l c m t trn bnh din quan nim, k tip l trn bnh din t chc v cui cng l trn bnh din tc nghip. + Mt th ba: Lin quan n chu k ca cc quyt nh - c trng c bn ca phng php MERISE + Nhn ton cc + Tch ri cc d liu v x l + Tip vn theo mc - u im: c c s khoa hc vng chc - Nhc im: Cng knh Phng php MCX (Methode de xavier castellani) Phng php phn tch MCX c ngun gc t Php - Mt s nt c bn v phng php phn tch MCX: + Cho php xy dng c m hnh tng qut, chnh xc, biu din HTTT hc cc phn h thng tin. + Cho php phn tch, nm c d liu, qu trnh x l v truyn thng cc HTTT + Cho php biu din cc x l vi cc lu v cc chng trnh, son tho bi 1 ngn ng gii thut dng cc mc khc nhau. + Cho php lng ho cc x l. - Cc giai on c bn ca qu trnh phn tch: + Phn tch macro + Phn tch s b + Phn tch quan nim

Phng php GALACSI (Groupe d Animation et de Liaison pour i Analyse et laConception de systeme d Information)

22

Phng php GLACSI c ngun gc t Php. Ra i thng 4/1982. Ni dung c bn trnh by mt tp hp c cng c v nguyn liu tin hnh cc giai on c bn sau y ca qu trnh phn tch: - Nghin cu cc h thng t chc v cc h thng thng tin tng ng: nghin cu hin trng, nghin cu kh thi - Phn tch chc nng: m hnh d liu, m hnh x l - Phn tch cu trc: t chc d liu, t chc x l, mi trng tip nhn, giao din ngi my. - Lp trnh Nhc im ca phng php ny l cha th nghim nhiu trong thc t. 1. Cch tip cn tin hc ho: 2 cch - Tin hc ho b phn - Tin hc ho ton phn Cu hi: + Nh th no iu kin tin hc ho ton phn ? + Hay iu kin tin hc ho c + xut tin hc ho b phn hay ton phn? + Bt u t u trc? iu kin tin hc ho c: + Khi lng thng tin nhiu (v d: x l kho) + Qu trnh hot ng n nh (v d: vic thu/chi) Tin hc ho ton phn: + Khi khi lng thng tin ln + Mi vic trao i thng tin c lm trong ton phn Phn loi h thng tin hc: + H thng mc b phn: qun l k ton + H thng mc x nghip : gii php ERP qun tr doanh nghip + H thng mc ton ngnh Cu hi: + Tin hc ho b phn Tin hc ho ton phn: l khng tt V: khng nhn thy c mt cch tng th, chp v + Gii php tng th: a ra c nn chung nguy c khng lng trc c vic dng chung s liu nn d dn n sai + Ton ngnh: ti chnh phn ra 3 cp Cp 1: cp TW: a ra chnh sch, b phn iu hnh Cp 2: a ra vn bn hng dn ca cp 1: trung gian gia 1 v 3 Cp 3: cp di + M hnh tin hc: l m hnh 2 cp:Cp di chuyn ln cp trn23

2. Phn tch thit k h thng c phng php

Cu hi: Th no l C phng php: (bn cht l phi tri qua cc bc theo phn tch TK HT c 1 phng php lun no ) Thc hin cc bc theo phng chm lm k 1 bc trc phng php? khi chuyn sang bc tip theo Cu hi: Ti sao lm Lm vic c phng php: vic c phng php - Trnh sai st (gim thiu mc sai st) - D t chc qun l thc hin (Khng quan trng nm) li c hiu qu hn ? - Hiu qu cao hn: (yu t ny quan trng nht) Cht lng tt hn khng chp v Nhanh hn v tin - D bo tr

3. Phng php lun phn tch thit k h thng c cu trc - Cu hi: V sao chn phng php lun PTTK c cu trc? Phng php lun PTTK c cu trc c c th g? - Phn tch h thng c cu trc l cch tip cn hin i ti cc giai on phn tch v thit k ca chu trnh pht trin h thng, c chp thun khc phc cc nhc im ca nhiu cch tip cn truyn thng. N s dng phng php lun bao gm: + B cng c, k thut, m hnh ghi nhn v phn tch h thng hin ti v cc yu cu mi t xc nh khun dng mi theo d kin. + Mt khun kh chung ch ra mi giai on s dng nhng cng c no v lin quan vi nhau ra sao Cc c th ca phng php lun c cu trc: (1) Phn tch h thng t 3 phng din: Chc nng, d liu, lung d liu (y va l u im, va l nhc im) u im: + So vi cc phng php trc y n quan st c c chc nng v phn tch d liu + n gin ho c bi ton Nhc im: Khng xem xt c mi quan h gia d liu v chc nng Khc phc: + Sinh ra m hnh lung d liu g ri cho nhc im ny + Sinh ra phng php lun hng i tng: quan st c hnh ng c d liu thng tin m i tng c (2) Cch tip cn TopDown: Xem xt s vt bt u t tng th chi tit ho dn dn tng bc

24

Lm g? M hnh chc nng

Mc tiu qun l

Dng Dliu g? M hnh d liu Ph n tc h

M hnh lung d liu

Thit k

Thit k

Thit k

Thi t k

(3) S dng 3 cng c kinh in trong phn tch thit k - BPC s phn r chc nng - BLD s dng d liu - ERD s quan h thc th C th l xy dng cc s : - S chc nng nghip v (BPC): Ch ra cc chc nng ca h thng cn thc hin - S lung d liu (BLD): Ch ra cc chc nng cng vi thng tin cn thit thc hin cc nhim v -S cu trc d liu (ERD): Ch ra cc thc th v mi quan h gia cc thc th trong c s d liu. 4. Cc phin bn khc nhau ca phng php lun phn tch c cu trc Chung: + BPC s phn r chc nng + ERD s quan h thc th Khc nhau: + Cc bc thc hin (hay s lng bc) + Cc cng c x dng th hin lung d liu 5. T chc xy dng h thng thng tin Phi c ban qun tr d n Trong cc nng lc sau chn ci no: + Nhng hiu bit v tin hc + C kh nng nghip v + Nng lc qun l25

Cu hi: Ngi qun l d n Tin hc phi c nng lc th no?

Qun tr d n cn quan tm + C kh nng nghip v + Nng lc qun l Nng lc qun l: + Xc nh mc ch nhanh + Bit iu phi, ch ra k hoch .. Lp k hoch: .. Kim sot .. Qun l ti chnh Qun tr d n: chia lm 2 khi Pha lp trnh Qun tr d n + Phn tch, thit k + Lp trnh vin K s trng Lp trnh vin + TestCase

+ Bit vic + Nng lc ca tng c nhn + Chi ph

Pha ngi dng Qun tr d n: 3 yu t + Ngi hiu c c li qui trnh nhim v, i din cho quyn li b phn iu hnh + i din cho b phn thc hin + nh hng

Vit Nam: a s khng c b phn lm cng vic kim chng chuyn nghip Cu hi: Trong trng hp khng c b phn Test th dng n v no lm? - Nn nh ngi s dng - Hay dng ngi phn tch - Khng cho ngi lp trnh vin lm v ngi ta ch nhn nhn h thng v mt k thut ch khng nm c nghip v K s trng lm g? - Nm v cng c tham gia vi thit k lm cng c lp ghp cc modul khc nhau vo h thng

Chng 4: Phn tch h thng v x l26

1. Mc ch, yu cu ca giai on phn tch 1.1. Mc ch - Nhn din v phn nh cc thnh phn v mi quan h trong h thng - u vo ca giai on ny l h s kt qu ca kho st h thng - u ra bao gm: + Biu chc nng nghip v (BPC - Bussiness Function Diagram) + Biu dng d liu (BLD - Data Flow Diagram) + Biu cu trc d liu (ERD Entity Relational Diagram) 1.2. Cch tin hnh - Xut pht t h thng c v cc nhu cu pht trin xy dng h thng mi - Chuyn t m t vt l sang m t logic hay ni cch khc l chuyn t mc vt l sang mc khi nim. - S dng k thut phn tch t trn xung (Top-down) hay i t tng th n chi tit. Phn tch h thng thnh 2 giai on con l phn tch h thng v x l v phn tch h thng v d liu. - C th tm tt giai on phn tch h thng v x l thng qua lc "How-What"

How?

M t h thng lm vic nh th no?

M t h thng mi lm vic nh th no?

What?

M t h thng lm vic g?

M t h thng mi lm vic g?

M t h thng lm vic g ch ra nhc im ca h thng c M t h thng mi lm vic nh th no ch ra u im ca h thng mi. 2. Biu phn cp chc nng (BPC - Bussiness Function Diagram) 2.1. Khi nim BPC l vic phn r c th bc n gin cc chc nng ca h thng trong min kho cu thnh cc chc nng nh hn, cui cng thu c mt cy chc nng. 2.2. Cc thnh phn ca BPC - K hiu chc nng l mt hnh ch nht bn trong l tn chc nng - Lin kt cc chc nng l ng thng27

Qun l kho

-Tn chc nng l ng t - b ng v ng t nn dng thc mnh lnh V d: Qun l XN

Qun l nhn s

Qun l ti chnh

Qun l vt t

Qun l h s

Qun l lao ng

2.3. c im ca biu phn cp chc nng - Cung cp cch nhn tng qut v chc nng ca h thng, phm vi cn phn tch - BPC trnh by cc chc nng ca h thng dng tnh, tc l khng th hin c mi quan h v chuyn giao thng tin gia cc chc nng, khng th hin trnh t thc hin x l thng tin. - Biu phn r chc nng thng c s dng b tr cho vic xy dng biu lung d liu. - Cht lng ca tn t cho cc chc nng l quan trng cho thnh cng ca h thng. Mi chc nng cn c mt tn duy nht, tn nn biu th tht st, y ngha ca cc chc nng con ca chc nng c t tn. Tn ca chc nng cn phi phn nh c cc chc nng ca th gii thc ch khng ch cho h thng thng tin. - Biu ny rt gn vi s t chc, tuy nhin khng c lm ln gia 2 s . V d: S c cu t chc ca x nghip: Ban gim c

Phng t chc

Phng KH, ti v

Phng vt t

Biu phn cp chc nng

Qun l x nghip

Qun l nhn s

Qun l ti chnh28

Qun l vt t

2.4. Cch xy dng BPC BPC th hin cc u vic m h thng cn thc hin t c mc tiu qun l (qun l ci g?), vic xy dng da trn c s ca bc kho st, v vy kho st cng k lng th vic xc nh m hnh chc nng cc y chnh xc. Mc tiu qun l Lm g? M hnh chc nng Thng tin c trn BPC: - Th hin y cc chc nng m h thng thc hin - Mt chc nng ln c th c phn thnh cc chc nng nh hn - Vic phn r c tin hnh theo tiu ch: + Theo bn cht x l (chc nng) + Theo b phn thc hin + Theo d liu phi x l Xy dng biu chc nng theo cc bc sau: - Xem c h thng l 1 chc nng duy nht, cn gi l mc 0 - Phn r khi chc nng mc trn thnh cc chc nng nh hn mc di, ln lt nh s l mc 1, mc 2, ...H thngMc 0

A

B

C

D

Mc 1

Mc 2

- Trong mc cao nht mt chc nng chnh s l mt trong nhng loi sau: - Qun l tin trnh sn xut. - Qun l cung cp dch v - Qun l ti nguyn, tin vn - Qun l con ngi ... T chc nng chnh ny chng ta phn r thnh cc chc nng con hnh thnh nn mt biu hnh cy m gc trn.29

- Thng thng i vi h thng ln cng khng nn c nhiu hn 6 mc (v kh theo di) v i vi h thng nh v trung bnh khng nn qu 3 mc. - Mt chc nng khng nn qu 7 chc nng con (kh theo di m hnh) - S nn tng i "cn bng" theo ngha mc ca cc chc nng con thp nht nn c xc nh tng ng nh nhau. - Phn tch chc nng a ra nhng chi tit quan trng m nhng chi tit s c dng nhiu nhng giai on sau ca phn tch. 3. Biu lung d liu (BLD - Data Flow Diagram) 3.1. Gii thiu v BLD Khi nim - BLD din t tp hp cc chc nng ca h thng v mi quan h chuyn giao thng tin gia cc chc nng hay ni khc i n cung cp bc tranh ng v h thng. - BLD c s dng l cng c c bn trong tt c cc giai on phn tch, thit k, trao i v lu tr d liu. Mc ch - Xc nh yu cu ca ngi s dng (NSD) - Lp k hoch v minh ho cc phng n cho nh phn tch v NSD xem xt - L cng c trao i gia nh phn tch v NSD do tnh tng minh ca BLD - Lm ti liu c t yu cu hnh thc v c t thit k h thng. Vic din t biu c chia thnh 2 mc: - Biu lung d liu mc vt l: + Trong biu mc vt l m t tt c cc chc nng x l, cc phng tin x l, cc gi mang thng tin (phng tin mang, vt mang) cng vi cc mi lin quan khng gian v thi gian. + Biu ny m t h thng lm vic nh th no (tr li cu hi "How?"), do vy n dng trong kho st h thng hin ti v thit k h thng mi - Biu lung d liu mc logic (mc khi nim, hay cn gi l mc quan nim) + Biu ny b qua yu t vt l, ch tp trung vo m t h thng lm g hay ni cch khc n tr li cu hi "What?" (m t h thng lm g?) + Biu ny ch quan tm n cc chc nng no cn x l trong h thng v nhng thng tin lin quan n chc nng . 3.2 Biu lung d liu mc vt l (Hay cc lu h thng) K hiu chung

30

Ho n xut

K hiu ring: Din t chi tit cc thng tin c lin quan n cc thit b

Trang in Danh sch di

Trng t

Ba c l

Bng t

Bng giy

a t Cc k hiu x l - K hiu chung - X l th cng Tn chc nng

Mn hnh

Sa h s

- X l nhp liu

Nhp tp

Phn r

Chn tp

Xp xp

K hiu ng truyn31

Chuyn giao thng tin ng truyn xa V d 1: M t bi ton v ng k mua hng v thanh ton c trnh by nh sau:Phiu ng k mua hng

Nhn n

T chi

Tp khch c chp nhn

n hng

Tp hng

Ho n

Phiu thanh ton

Ghi nhn n hng

Tp khch ghi nhn n

Lp ho n

Tp khch ghi ho n

Ghi nhn thanh ton

n khng gii quyt c

hng, b phn ny duyt phiu ng k nu khng gii quyt th tr li cho khch hng, ngc li th lu tr li phiu ng k. B phn ghi nhn n hng cn c vo n mua hng ca khch cng vi cc phiu ng k c duyt lc ra nhng n hng khng th p ng c v nhng n hng c th p ng c. Cc n ny chuyn cho b phn lp ho n. B phn lp ho n tra cu thng tin v hng cng vi n hng chp nhn vit thnh ho n. Mt lin tr li cho khch v 1 lin gi li. B phn thanh ton cn c vo t ho n trn thanh ton cho khch hng. Khi thanh ton phi lm thnh 2 lin, 1 lin tr li cho khch, 1 lin lu tr li. (s ny cn c mt cch gi khc l s lun chuyn thng tin trong h thng.)

Phiu ghi nhn thanh Tp khch Khch hng mun mua hng phi gi 1 phiu ng thanh tonb phn ton nhn khch k cho ghi

32

V d 2: Qui trnh x l bi ton qun l kho Nh cung cpHn g

B phn khoNhp hng

K ton khoPNhp

n v nhn

Lnh o

Kho Hn g Xut hng Phiu xut

Tng hp tn

Bo co th kho th kho

Lu : - Xc nh xem cc b phn tham gia x l nm ct no - V vo s nhn thng tin hay sinh ra u ra - Gia 2 hnh bnh hnh khng c mi tn (Cc thc th) - Gia 2 hnh ch nht c th c mi tn - C nhng thng tin g s ny Cc chc nng m h thng phi thc hin: l hnh chc nht Thng tin d liu: Hnh bnh hnh Lung d liu n v tham gia qun l: B phn kho, K ton kho, Lnh o 3.3 Biu lung d liu (BLD- Data Flow Diagram) 3.3.1. Cc thnh phn ca biu + Chc nng x l (Process) + Lung thng tin (Data Flows) + Kho d liu (Data Store) + Tc nhn ngoi (External Entity) + Tc nhn trong (Internal Entity) Cc chc nng x l (Process) - Khi nim: Chc nng l mt qu trnh bin i thng tin -K hiu chc nng33 Tng hp tn

- Tn chc nng: C dng ng t + b ng nu cn, cho php hiu mt cch vn tt chc nng lm g. Trong thc t tn cc chc nng phi trng vi tn t cho cc chc nng trong s chc nng nghip v. V d: Ghi ho n, nhp h s, . . . Lung d liu (Dng d liu Data Flow) - Khi nim: y l lung thng tin vo hoc ra ca 1 chc nng x l. - K hiu lung thng tin: L mt ng k c mi tn, trn c vit tn ca lung d liu

Tn lung d liu phi l mt danh t, km thm tnh t nu cn, cho php hiu vn tt ni dung ca d liu c chuyn giao V d: Ho n kim tra, n hng duyt, H s sinh vin.... Lung d liu thng gn vi 1 chc nng no Tr 1 s trng hp c th, ni chung mi lung thng tin u phi c tn. Tn ny khng nht thit phi l duy nht, theo ngha cng thng tin c th i vo mt s tin trnh, nhng m bo rng cc dng thng tin khc nhau c mang cc tn khc nhau. Nhng thng tin no c thay i th nn c mang tn sa i biu th r iu . V d:H s H s duyt

Duyt h s

Ch : Cc dng d liu v tn c gn cho chng phi ch ra c thng tin "logic" tng ng ch khng phi l ti liu vt l. Kho d liu (Data Store) - Khi nim: Mt kho d liu l mt d liu (n hay c cu trc) c lu li c th c truy nhp nhiu ln v sau. - K hiu:

- Tn kho c dng Danh t + tnh t nu cn v cho php hiu mt cch vn tt ni dung ca d liu c lu d. V d: H s cn b, ho n nhp, im mn hc, Danh sch gi.... - Lin quan gia kho v chc nng c cc tnh hung nh sau:34

+ Ct hay ghi d liu vo kho Hiu chnh gi c Nhp h s

+ c d liu t kho

Danh sch gi

H s cn b

Danh sch gi

H s cn b

+ Cp nht d liu trong kho

Ln gi n hng

Tm kim

Trong cc trng hp ny tn lung d liu khng phi c hiu l tn khoHiu chnh h s B tr kho cho n hng

ghi v

H s cn b

Tp kho

Tc nhn ngoi (External Entity) L 1 ngi, 1 nhm ngi, 1 t chc hay 1 i tng (thc th) bn ngoi h thng, nhng c trao i thng tin vi h thng. S c mt ca cc nhn t trn s ch ra gii hn h thng v nh r mi quan h ca h thng vi th gii bn ngoi. iu quan trng cn hiu l "ngoi lnh vc nghin cu" khng nht thit l bn ngoi t chc. VD: vic nghin cu h thng x l n hng ang c xem xt th b phn k ton, b phn mua hng v cc b phn kho tng c th u l nhn t bn ngoi. Nhn t bn ngoi l phn sng cn ca h thng, chng l ngun gc cung cp thng tin cho h thng v l ni nhn cc sn phm ca h thng. - K hiu tc nhn ngoi l mt hnh ch nht35

- Tn tc nhn ngoi l Danh t VD: Khch hng, Nh cung cp, sinh vin, Gio vin, Phng o to... Tc nhn trong (Internal Entity) - y l 1 chc nng hay l 1 h thng con ca h thng ang kho st c m t trang khc ca biu . - K hiu: Hnh ch nht thiu 1 cnh, c ghi tn l ng t km b ng VD: cung ng vt t Mua hng Chc nng x l th cng Mt s ch trong biu lung d liu: Trong biu khng c 2 tc nhn ngoi trao i vi nhau Khng c trao i trc tip gia 2 kho d liu m khng thng qua chc nng x l Bn hng hoc T/D DM vt t

Kho c tn, nn lung d liu vo kho khng cn tn, ch khi vic cp nht, hoc trch t kho ch mt phn thngtin kho, ngi ta mi dng tn cho lung d liu V l do trnh by nn tc nhn ngoi, tc nhn trong v kho d liu s dng nhiu ln c th c v li nhiu ni trong cng biu d c, d hiu hn i vi kho d liu phi c t nht 1 lung vo v t nht mt lung ra. Nu kho ch c 1 lung vo v khng c lung ra l kho V tch s, ch c lung ra v khng c lung vo l kho Rng Tc nhn ngoi khng trao i vi kho d liu m phi thng qua chc nng x l Trong biu lung d liu c khi no khng c tc nhn ngoi khng ? Ti sao?: Tc nhn ngoi l phn sng cn ca h thng, chng l ngun cung cp thng tin cho h thng cng nh chng nhn sn phm thng tin t h thng 3.3.2. Phng php xy dng biu dng d liu (BLD)

36

- BLD cng c chia thnh cc mc tng ng vi cc mc trong biu phn cp chcnng (BPC) C 3 mc c bn c cp n: + Mc 0: B lung d liu mc khung cnh (Context Data Plow Diagram) + Mc 1: Biu lung d liu mc nh (Top level Data Plow Diagram) + Mc 2: B lung d liu mc di nh( Levelling Data Plow Diagram)

Biu lung d liu mc khung cnh (Context Data Plow Diagram): y l m hnh h thng mc tng qut nht, ta xem c h thng nh 1 chc nng. Ti mc ny h thng ch duy nht c mt chc nng. Cc tc nhn ngoi v ng thi cc lung d liu vo ra t tc nhn ngoi n h thng c xc nh S ng cnh bao gm 1 vng trn trung tm biu th ton b h thng ang nghin cu l mt chc nng c ni vi mi tc nhn ngoi h thng. Cc ng ni th hin thng tin vo - ra h thng. Ta c th xy dng BLD t s ng cnh ny. + S ng cnh (cn gi l BLD mc khung cnh - mc 0 ) Ban gim hiuBo co

th H c nhn ng T Lung dl3 x Lung dl1 l Y i m Thng bo Hc sinh Biu lung d liu mc nh (Top level Data Flow Diagram) - BLD mc nh (mc 1): y l s phn r trc tip t biu mc khung cnh v phi p ng 1 s yu cu sau y khi phn r: + Bo ton cc tc nhn ngoi v cc lung thng tin vo/ra ca h thng + Thay th 1 chc nng duy nht ca h thng bi nhiu chc nng con + B sung thm cc lung d liu ni b v cc kho d liu cn thit

- Qui ch o to - Yu cu H qun l Thng tin

X

Lung dl2

X C B K X D37

Biu lung d liu mc di nh ( Levelling Data Plow Diagram)

- Cc chc nng c nh ngha ring tng biu hoc ghp li thnh 1 biu trong trng hp biu n gin - Cc thnh phn ca biu tun th nguyn tc: + V chc nng: phn r CN cp trn thnh CN cp di thp hn + Lung d liu: vo/ra mc trn th lp li mc di, b sung thm cc lung d liu do phn r cc chc nng v thm kho d liu + Kho d liu dn dn xut hin theo nhu cu ni b + Tc nhn ngoi: xut hin y mc khung cnh, mc di khng th thm g. - V d: t mc nh ta c di nh nh ngha nh sau:

B=EFX

C=IJK K

D=HLJ

E

FK H L

I K1 Y X

- BLD mc di nh: T mc 2 tr i, c gi l mc di nh. Khi phn r chc nng h thng t BLD mc nh, s nhn c biu mc di nh, theo nguyn tc: + Thay th 1 chc nng mc nh bng 1 BLD mi c mt hoc mt s chc nng, c th xut hin thm cc lung d liu lin h v cc kho d liu mi trong biu + Bo ton cc tc nhn ngoi vi cc lung thng tin vo ra h thng - d theo di qu trnh phn r, tin hnh nh s cc chc nng theo kiu chng/mc 1.1 1 2 1.2 1.1.1 1.1.2 1.2.1 1.2.2

1.2.3 S mc phn r ph thuc vo tng bi ton v tu thuc vo yu cu ca giai on sau. C th qu trnh phn r dng li khi xc nh r c chc nng l chc nng th cng hay chc nng my tnh. V d 1: Hot ng ca qu tn dng

38

Khch hng mun vay tin tn dng, phi lm n vay. n ny c chuyn n b phn cho vay ca qu. B phn ny tin hnh duyt n vay ca khch tr li gii quyt cho vay hoc t chi. Cn c duyt do qu tn dng quy nh: khi 1 n c chp nhn, qu tn dng thc hin cho khch vay, ng thi ghi thng tin vo s n Khi khch hng mang tin n tr, b phn thu n tin hnh xc nh phn loi khch tr ng hn v khng ng hn tnh cc li sut tng ng v cp nht vo s ghi n. Mc tiu qun l: - Theo di vay: Nhn n Duyt vay Tr li n - Theo di thu n: Xc nhn tr ng hn Xc nh k hn tr Xc nhn tr ng hn yu t thnh cng ca bi ton: S n BPC ca h thng nh sau:Hot ng tn dng

Thu n

Cho vay

Xc nhn tr ng hn

Xc nhn tr KH ng hn

Nhn n

Duyt n n vay

Tr li n

BLD mc khung cnh

Khch vay

Tr li n Hon tr

BLD mc nhn vay

H thng qu tn dng

Cho vay 1

Ghi n

Khch hng39 Thu n 2

Danh sch n

Hon tr

BLD mc di nh chc nng 1n vay

Khch vay

Nhn n 1.1

n nhn

Duyt n 1.2

n tr li

Tr li n 1.3

n duyt

Danh sch n

BLD mc di nh chc nng 2

40

Khch vayTr ng hn Cp nht tr ng hn 2.2

Xc nh loi tr 2.1Tr khng ng hn Cp nht tr khng ng hn 2.3

V d 2: Chng trnh

Xy dng BPC v BLD ca bi ton qun l Nhn s - Tin lng ca mt Cng ty vi cc yu cu sau: - Qun l nhn s: + p ng c yu cu cp nht v lu tr h s nhn vin trong cng ty (trong c c lng c bn v ph cp chc v nu c) + Xem l lch ca bt k nhn vin khi c yu cu + iu chnh l lch nhn vin: iu chnh thng tin v h s l lch, xo.... - Qun l tin lng: tnh lng da vo s chm cng ca cc b phn v cc thng tin v lng c bn, h s ph cp,.... trong h s nhn vin. Chng trnh cn p ng c: + Nhp s chm cng hng thng ca tng nhn vin + Thay i s liu chm cng + Tnh lng theo qui nh cho tng nhn vin + Thng k lng theo tng b phn + Thng k lng ton n v.

Tr tin

Danh sch n

qun l Nhn s - Tin lng

BPC:

qun l nhn s tin lng

qun l nhn sThng tin nhn s Yu cu

qun l tin lng

BLD:

nv

Bo co

thm Ban gim c hiu mi chnh Phng T chc nv

tra t.tin nv

chm cng nv

iu chnh c.cng

bo co lng

+ Biu khung cnhqun l nhn s tin lng 41 Bo co lng Yu cu

Thng tin ngy cng

Phng k ton

B phn chm cng

+ BLD mc nhBan gim c Phng T chc Phng k ton B phn chm cng

Qun l Nhn s 1

H s nhn vin

Bng chm cng

+ BLD mc di nh chc nng 1:vin H s nhnThng tin NV mi Ban gim c Phng T chc

Qun l Tin lng 2Yu cu iu chnh

Cp nht h s NV 1.1 Lu thng tin H s nhn vin

iu chnh h s NV 1.2

chc

Thng tin theo yu cu Ban gim c Qui nh mc thng, pht Yu cu Tra cu Phng T chc B phn chm cng tin Ban gim c thng Phng T chc N.vin 1.3 Thng tin Bo co kt qu + BLD mc di nh ngy cng iu

Chm cng 2.1

chnh chm cng 2.2Bng chm cng

nng 2:

H s nhn vin

Tnh lng & Bo co 2.3

Yu cu tnh lng 42 Kt qu lng

Phng K ton

V d tng hp:

Bi ton cung ng vt t nh my X

Hot ng cung ng vt t nh my X c m t nh sau: Khi 1 phn xng c yu cu v vt t sn xut, th phn xng phi lp bn d tr gi ln b phn t hng ( t hng). B phn ny tip nhn bn d tr ca cc phn xng, tp hp li sau tin hnh thng lng vi cc khch hng ( c hoc cha c giao dch). Sau khi tho lun vi khch hng b phn t hng lp n hng v chuyn cho ngi cung cp. Ngi cung cp mang hng n nh my giao cho b phn nhn hng, b phn ny c chc nng nhn hng ca ngi cung cp ng thi pht hng v cho cc phn xng. Khi nhn hng h phi thc hin ghi nhn vi ngi cung cp s hng nhn thng qua cc phiu giao hng. Do h khng gi cc bn d tr nn h khng th t ng pht hng cho cc phn xng. ng thi h khng nm gi n hng nn cng khng th bit hng nhn c ng nh yu cu t mua hay khng. Do 2 h thng t hng v pht hng hot ng vi nhau nh vy nn nh my phi c 1 b phn i chi th cng thc hin cc cng vic sau: 1. i chiu hng nhn vi n hng pht hin nhng sai lch trao i vi khch hng. 2. Kim tra li s hng nhn do b phn nhn hng bo li so vi ho n m khch hng mang n thanh ton, nu c sai st phi trao i li vi khch hng. Sau khi hon tt th tc i chiu, b phn i chiu s thng bo cho b phn pht hng thng tin v cc phn xng v hng m h d tr. B phn pht hng s tin hnh giao hng cho cc phn xng. ng thi, b phn i chiu gi cho b phn thanh ton xc nhn s tin cn phi tr cho ngi cung cp. B phn thanh ton giao tin cho ngi cung cp v bo li cho bn t hng bit l n hng gii quyt xong. Thc hin bi tonQun l vt t

Cc chc nng chnh ca h thng bao gm: - t hngt hng Pht hng

- Nhn v pht hng - i chiu i chiu - Thanh ton

Thanh ton

Hai tc nhn ngoi l : - Phn xng Tm BPCLp ngi n cung hng cp In danh sch n hng Ghi Ghi Ngi cung cp (Ngi CC) nhn i Lp In nhn giao danh phiu hng chiu hng n sch pht v hng hng 43 nhn & hng hng nhn Xc nh /c pht hng Ghi nhn tr tin Khp ho n & hng v

BLD mc khung cnh

Thng lng n t hng

NCC

D tr Phn xng

H cung ng vt t

Phiu giao hng Ho n Tin

Ho n sai Phiu pht hng D trPhiu pht hng

Hng sain hng

NCCNgi CCPhiu giao hng

BLD mc Phn xng di nhD tr

Khch hngt hn g DS n hng

Thng lng Tin tr Tr tin

n hng

Xc nhn thanh ton i chi u

Ho n

Danh sch nhn hng

Hng nhn

a ch pht hng 44

Nhn & pht hng

3.4. Chuyn t BLD mc vt l sang mc logic 3.4.1. BLD mc vt l - Trong biu mc vt l cn chc cc yu t vt l bao gm cc phng tin, a im, ngi thc hin chc nng. - Khi cc yu t vt l c mt trong biu s gy cn tr cho vic khi qut ho cc chc nng cu h thng, kh hiu c bn cht ca quy trnh x l. 3.4.2. BLD mc logic L biu BLD trong khng cn cha cc yu t vt l 3.4.3. Cch thc chuyn t BLD mc vt l sang mc logic - Loi b cc ngn t lin quan n phng tin, phng thc hay gi mang thng tin. - Loi b cc chc nng gn lin vi bin php, ch gi li cc chc nng gn vi ni dung (duyt xem, thng lng, in ra giy....) -T chc li biu : C th gom mt s chc nng gn nhau mc di thnh 1 chc nng mc trn. V d: Bi ton cung ng vt t Biu mc di nh ca chc nng 1 (t hng) NCCn t hng n hng

Lp n hng 1.2Nh CC chn s hiu H d tr

D tr n hng

In DS n hng 1.3DS n hng

Thng lng Phn xng

Chn NCC 1.1Ngi cung cp

i chiu

D tr45

BLD mc di nh chc nng 2 (Pht hng)i chiu

NCCPhiu giao hng

Danh sch hng nhn

/c pht hng

In DS hng nhn 2.2

Ghi nhn hng v 2.1

Lp phiu pht hng 2.3Phiu pht hng

Phn xng BLD mc di nh ca chc nng 3 (i chiu)Hng nhn t hngDS n t hng Hng sai

Ghi nhn giao hng 2.4

NCCHo n sai Ho n

Xc nhn tr

Tr tin

Khp n hng & hng nhn 3.1n i chiu xong DS hng nhn

Khp ho n v n hng 3.3

n hng

Xc nh /c pht hng a ch pht hng 3.2 BLD mc di nh ca chc nng 4 (Thanh ton)Xc nhn tr 4.1 In phiu thanh ton 4.2 Phiu thanh ton Xc nhn thanh ton

Pht hng

*Loi b yu t vt l

i chiu

Ngi CC

46

- Pht hin v loi b cc chc nng vt l: Trong h thng c 2 chc nng 1.3, 2.2; l 2 chc nng in n, loi b 2 chc nng ny. - Chn tn l gc ph hp: Chc nng 4 tr tin i thnh thanh ton; * Ci tin cc thao tc th cng * T chc li biu nh sau - Chc nng 1.1 - Chc nng 1.2 - Chc nng 2.1 - Chc nng 3.1, 3.3 - Chc nng 2.3 - Chc nng 3.2 - Chc nng 4.1, 4.2 : thnh chc nng : : : : : : 1 (Chn ngi cung cp) 2 (Lm n hng) 3 (Ghi nhn hng v) 4 (Kim hng v) 5 (Lm phiu pht hng) 6 (Xc nh a ch pht hng) 7 (Thanh ton)

Sau khi loi b cc yu t vt l, t chc li cc chc nng ta c BLD ph hp nh sau:

BLD sau khi gp ( mc logic)n hng

Nh cung cpHo n Ho n sai

S hiu n

Lp n hng 2

Kim hng v 4Xc nhn

Phiu thanh ton

TTn hngXc nh a ch pht hng 6

Ho n

Thanh ton 7

D tr

D tr/n hngChn NCC 1

Hng nhn

Ghi nhn hng v 3

Thng lng

Nh C.cpD tr

3.4.4. Hon thin BLD ca h thng miPhn xng

Nh cung cp

Lp phiu pht hng 5Phiu pht hng

- Xem xt nhng nhc im ca h thng c, cc yu cu, mc ch ca h thng mi

47

Phiu giao hng

a ch pht hng

- Xem xt BLD ca h thng c xc nh nhng ch tha, thiu v nhng ch c bin i nhiu. T thc hin khoanh vng mt s cc thay i trong cc vng khoanh, c th cc chc nng v vng d liu theo nguyn tc sau: - Bo ton lung d liu vo/ra ca vng - Xc nh chc nng tng qut ca vng thay i - Xo ton b biu trong vng v v li theo nh hng sau: - Cc trung tm bin i v trc - Bin i trng thi t vo thnh ra - C th thm cc kho, lung d liu vo trong h thng. V d: Bi ton cung ng vt tNh cung cpn hng Ho n Ho n sai

S hiu n

Lp n hng 2

Kim hng v 4Xc nhn

Phiu thanh ton

TTn hngXc nh a ch pht hng 6

Ho n

Thanh ton 7

D tr

D tr/n hngChn NCC 1

Hng nhn

Ghi nhn hng v 3

Thng lng

Nh C.cpD tr

Nh cung cp CN1

Lp phiu pht hng Tn kho 5 Qun l kho 9

CN 5

Phiu pht hng Duyt d tr Phn xng 8

Phn xng

48

Phiu giao hng

a ch pht hng

Chng 5: Phn tch h thng v d liuNi dung: M hnh thc th lin kt ER (Entity Relationship) M hnh quan h (Relation Base Modeling) 1. Mc ch, yu cu ca vic phn tch d liu 1.1. Mc ch ca giai on - Gip cho vic t chc cc kho d liu mt cch hp l, y , v chun mc. - Xy dng c lc cu trc d liu (BCD). Trong lc ny cho bit c: + Cn lu tr nhng thng tin g? + Mi lin h gia cc thng tin? 1.2. Yu cu - Trnh b st: cn g phi c y - Trnh trng lp: V d khai nm sinh khng cn phi khai tui - Trnh nhp nhng: Loi b tnh a tr ca thng tin - Khi phn tch ta cha quan tm n cc yu cu v tnh sn dng, tnh ti u trong lu tr v truy nhp. 1.3. Phng php thc hin: C 2 phng php tip cn: + Dng m hnh thc th - lin kt: cn c gi l cch nhn t trn xung (Top down) v cung cp ci nhn trc quan i vi d liu + S dng m hnh quan h: Tip cn t di ln (BottomUp). C th: xut pht t nhng thng tin cn phi kt xut ra i ngc ln hnh thnh lc quan h. Cung cp thng tin mc va cho yu cu x l hin ti. 2. Biu cu trc d liu theo m hnh thc th lin kt (ER entity relation ) 2.1. S thc th - S thc th xc nh cc n v thng tin c s cn thit cho h thng (cc thc th) v mi quan h gia chng (iu ny c ngha l tt c d liu ch lu tr mt ln trong ton b h thng v c th thm nhp t bt c chng trnh no). - Trong thc t c nhiu m hnh biu din, phm vi chng trnh ta nghin cu mt loi m hnh l m hnh quan h. D liu lu tr trong h thng di dng tp cc bng. S thc th lin kt s xc nh trong h thng c bao nhiu bng v mi quan h gia chng. 2.2. Cc thnh phn ca s thc th - Thc th: L mt i tng, mt s kin cn c lu tr thng tin VD: mi khch hng l mt thc th v n th hin bng mt dng trong bng

49

- Kiu thc th: L tp cc thc th c cng tnh cht, m t cho mt loi thng tin (bn thn n khng phi l thng tin). Trong s m hnh E-R, kiu thc th c k hiu c dng hnh ch nht. N tng ng vi cu trc ca mt bng. VD: Khch hng l mt kiu thc th v n m t tng thc th khch hng -Thuc tnh 1 - Thuc tnh 2 ... -Thuc tnh n

Kiu thc th c xc nh + Lin quan n thc th mang thng tin

+ Lin quan n i tng qun l hoc mang tnh thng k + Thng tin lin quan ti mt giao dch ch yu ca h. (VD: n t hng,...) + Thng tin lin quan n thuc tnh hoc ti nguyn ca h. (VD: Kho, Nh cung cp, Khch hng,...) + Thng tin khi qut di dng thng k lin quan n lp k hoch hoc kim sot. (VD: Bng lng, lch iu xe,...) - Thuc tnh: Mi thc th bao gm nhiu thng tin, mi thng tin l thuc tnh ca thc th. C 3 loi thuc tnh bao gm: + Thuc tnh kho: Gm mt hay nhiu thuc tnh trong Kiu thc th c dng xc nh duy nht mt thc th. VD: Thuc tnh S hiu khch hng l thuc tnh kho cho kiu thc th Khch hng. iu ny c ngha l mi khch hng trong bng u phi c mt s hiu khch hng khc nhau. Thuc tnh tn khch hng c th l mt ng c vin cho kho, nhng bao gi cng c kh nng trng tn gia hai hoc nhiu khch hng. + Thuc tnh m t: Hu ht cc thuc tnh trong mt kiu thc th u c nhim v m t cho thc th c ni ti, thng tin ny lm tng hiu bit ca ta v thc th v phc v cho cc mc ch qun l ca h thng. + Thuc tnh kt xut: L thuc tnh m gi tr ca chng c tnh ton t cc thuc tnh khc. + Thuc tnh kt ni (kho ngoi): Dng xc nh mi lin kt gia cc kiu thc th. l thuc tnh trong mi quan h ny l thuc tnh kho nhng trong mi quan h khc ch l thuc tnh m t. Vic xc nh thuc tnh ny kh tru tng v kh khn. - Lin kt (mi quan h) v kiu lin kt + Lin kt l ch ra 1 s kt ni c ngha gia 2 hay nhiu thc th phn nh s rng buc v mt qun l. (VD: quan h gia gio vin vi hc sinh) + Kiu lin kt: l tp hp cc lin kt c cng bn cht50

- Cc kiu lin kt: + Lin kt 1-1

A

1

1

B

Thc th A gi l c quan h 1-1 vi thc th B VD:Con ngi Sinh vin Chng minh th Th SV

+ Lin kt 1- n Thc th A c gi l lin kt 1-n vi thc th B Lp1 n

HS

VD: lp c nhiu hc sinh;1 hc sinh thuc vo 1 lp no + Lin kt n- n Thc th A c gi l lin kt n-n vi thc th Bn

A

n

B

VD: Mt gio vin dy nhiu mn hc; 1 mn c dy bi nhiu gio vinNhn vin Li xe Sinh vin

Cng vic

Phng tin

Mn hc

- xc nh cc kiu lin kt phi da vo cc lin t trong mnh din t quan h. V d: c, ca, thuc vo, cho.... - Trn thc t khi x l mi quan h nhiu - nhiu ngi ta a thm vo 1 thc th trung gian tch quan h nhiu - nhiu thnh 2 quan h 1-nhiu (quan h n-n l khng r rng, d nhp nhng khng s dng c)n n n n

A V d 1:

B

A

A/B

B

Nu thm vo thc th ph:Li xe Phiu iu ngNgy iu ng Xe no Li xe no

Phng tin

51

Th quan h trn s c chuyn:

Li xe Phiu iu ng Phng tin

V d 2:Nhn vin Nhn vin

xV dCng vic Sinh vin Cng vic Gio vin

Bn phn cng

3:

Sinh vin

Gio vin

Thi kho biu

Sinh vin

Gio vin

Thi kho biu

Lp

Trong v d ny phn r quan h n-n phi qua 2 cng on, thm vo thc th thi kho biu v lp. Ch : C 1 s quan h dng qui nh sau: + Quan h qui 1-n: Mt thc th c th quan h vi nhiu thc th di quyn thuc cng 1 kiu, nhng tng thc th di quyn ch c mt thc th cp trn c lin quan vi n. VD: Kiu thc th "Nhn vin" thng cha 1 quan h qui.

Nhn vin

52

+ Quan h qui n-n: Tng thc th trong bng c th c quan h vi mt s cc thc th di quyn trong cng mt bng v cng c ngha l tng thc th di quyn c th c mt s cc thc th cp trn trong cng quan h. VD: C mt s tha t c hp li, ri cc tha ny li c tch ra miTha

# S hiu tha ..... ......chi tit tch nhp

# S hiu tha mi @ # S hiu tha c @

2.3. Xy dng s thc th - lin kt 2.3.1. La chn m hnh Hin nay trong cc bi ton vn s dng ch yu l m hnh quan h 2.3.2. Pht hin kiu thc th - T cc ngun ti nguyn nh: vt t, ti sn, con ngi, mi trng - T cc giao dch: nhng lung thng tin n t mi trng bn ngoi v lm kch hot 1 chui hot ng no ca h thng (khi c 1 n hng cung cp n th b phn nhn hng mang hng n kho, chuyn qua b phn k nhn,...) - Nhng lung thng tin cu trc ho (VD: th th vin, s theo di kho sch,...) 2.3.3. Pht hin cc kiu lin kt (1-1; 1-n; n-n) - Ch ghi nhn cc kiu lin kt c ch trc tip cho bi ton qun l (VD: Qun l nhn s: ch n nhng lin kt c lin quan n qun l nhn s) - xc nh c kiu lin kt phi cn c vo lin t theo cc mnh m t v d liu, m t v quy trnh, quy phm qun l v x l thng tin. C cc kiu lin kt sau: 1-1, 1nhiu, nhiu-nhiu. VD: Quan h GV v mn hc Gio vin Mn hc

+ Nu quy nh mi gio vin ch dy 1 mn th y l quan h 1-nhiu + Nu mi gio vin dy nhiu mn th y l quan h nhiu-nhiu - Trc khi thnh lp biu cu trc d liu (BCD) phi gii trnh quan h gia cc thc th. - Nu gia 2 thc th c quan h nhiu-nhiu thng tch thnh 2 cp quan h 1-nhiu bng cch a vo 1 thc th trung gian. 2.3.4. Pht hin thuc tnh + Thuc tnh kho + Thuc tnh m t53

+ Thuc tnh kt xut (thuc tnh ny c loi b khng a vo danh sch. + Thuc tnh kt ni- M ngi mua - H tn - a ch - M hng - Tn hng

M ngi mua M hng

V d minh ho: Tr li bi ton cung ng vt t, tin hnh pht hin cc thc th nh sau: (1) Xc nh thc th: - Thc th mang thng tin: D tr, Ho n, n hng, Giao hng, Pht hng - Thc th l i tng qun l hoc mang tnh thng k: Ngi cung cp, Phn xng, Mt hng (2) Xc nh quan h gia cc thc th (3) Chun ho cc quan h (bin i cc lin kt n-n thnh lin kt 1-n) (4) Xc nh cc thuc tnh ca thc th Ta thu c s E-R nh sau: Phn xng* SHPX Tn PX M t * SHDT + SHPX Ngy DT

Phiu pht hng Phiu pht hng Dng pht hng

* SHPH + SHPX - Ngy

Phn xng D tr

* SHPH *MH - S lng

D tr Dng d tr

* SHDT + MH S lng

n n Dng hng hng

* SHH * MH - S lng

Mt hng

Ngi cung cp n hng

* SHn - Ngy + SHNCC

Ho n Mt hng

* MH Tn hng VT n gi * SH MH Soluong

MH/NCC* SHNCC * MH

Ngi cung Phiu giao hng cp

* SHNCC Tn ach * SHGH * SHNCC Ngy

Dng ho n

Phiu giao hng

Ho n

* SH * SHNCC - Ngy

Dng giao hng54

* SHGH * MH - Lng

55

3. Hai cch tip cn thit k c s d liu quan h 3.1. Chun ho theo hng phn tch: Thc hin chun ho dn dn theo 3 bc 1NF, 2NF, 3NF (1) a v dng chun 1: tch cc thuc tnh lp (khng n) Nhm cc thuc tnh n (cn li) to thnh 1 quan h. Chn kho cho chng. Nhm cc thuc tnh lp c tch ra, tng thm kho ca quan h trn to thnh 1 quan h (hay 1 s quan h theo ch ). Chn kho cho (cc) quan h ny, thng l kho bi, trong kho ca quan h trn l mt thnh phn.

=> Cc quan h u l 1NF (2) a v dng chun 2 : - Tch cc nhm thuc tnh ph thuc hm vo mt phn ca kho. - Nhm cn li to thnh mt quan h vi kho nh c - Mi nhm tch ra (gm cc thuc tnh cng ph thuc vo mt (hay 1 s) thuc tnh no ca kho) tng thm (cc) thuc tnh m chng ph thuc to thnh mt quan h, vi cc kho l (cc) thuc tnh tng thm ny. = > Quan h lp c u l 2NF (3) a v dng chun 3 : - Tch cc nhm thuc tnh ph thuc hm vo mt (hay mt s) thuc tnh ngoi kho. - Nhm cn li to thnh mt quan h vi kho nh c. - Mi nhm tch ra (gm cc thuc tnh cng ph thuc vo mt (hay mt s) thuc tnh ngoi kho) tng thm (cc) thuc tnh m chng ph thuc, to thnh mt quan h, vi kho l (cc) thuc tnh tng thm ny. => Cc quan h c lp u l 3NF V d 1 : Trn mt n hng, ta gom c danh sch cc thuc tnh nh sau : + Cc thuc tnh n : SH-H SH NCC Tn NCC Ch NCC NgyH Tng cng + Cc thuc tnh lp: M MH56

M t MH VT SL t ngi Thnh tin Cc thuc tnh Thnhtin v Tng cng l cc thuc tnh tnh ton, b loi khi danh sch. + Cc PTH tm c: F = {SH- H -> SH NCC, Tn NCC, DCh NCC, Ngy H SH- H, MH -> MtMH, VT, ngi, Slng t SH-NCC -> TnNCC, achNCC MMH -> MtMH, VT, n gi } Chng t giao dch: n hng Danh sch thuc tnh SH-H SH NCC Tn NCC Ch NCC NgyH M MH TnMH M t MH VT ngi SL t 1NF # SH-H SH NCC Tn NCC Ch NCC NgyH # SH- H # M MH TnMH M t MH VT ngi SL t 2NF # SH-H SH NCC Tn NCC Ch NCC NgyH # SH- H # M MH SL t # M MH TnMH M t MH VT 3NF # SH-H SH NCC NgyH # SH NCC Tn NCC Ch NCC # SH- H # M MH SL t # M MH TnMH M t MH VT Cui cng ta thu c 4 quan h: n hng (SH-H, SH NCC, Ngy) NgCCp (SH NCC, tn NCC, a ch NCC) Dng H (SH-H, MaMH, SL t) Mt hng (MMH, TnMH, VT, M t) 3.2. Chun ho theo hng tng hp:57

Cch lm ny cho ngay ra cc lc quan h 3NF m khng qua cc giai on 1NF, 2NF (1) Xut pht t danh sch cc thuc tnh. Tm cc PTTH trong danh sch cc thuc tnh (2) Lp th cc PTH: - Mi thuc tnh trong danh sch l 1 nt - Mi nhm thuc tnh l v tri ca PTH cng l mt nt - Nu c PTH A->B th v mt cung ni nt A ti nt B (3) a th v ph ti thiu ca n: - Hoc lm bng tay, m bin i ch yu l loi b cc cung kp kn hnh tam gic. - Hoc lm bng my tnh Trn cc th ch cn cc PTH trc tip (4) Dng cc hnh ch nht khoanh vng trn th thnh cc quan h nh sau: mi nt trong (tc l nt con) ly lm kho, hp thnh vi cc con ca n lp thnh 1 quan h cc quan h u l 3NF V d : F = {SH- H -> SH NCC, Tn NCC, DCh NCC, Ngy H SH- H, MMH -> MtMH, VT, ngi, SL t SH-NCC -> TnNCC, achNCC MMH -> MtMH, VT, n gi } Thm cc PTH tm thng SH- H, MH -> SH- H, MH SH- H, MH

SH- H

SL t

MMH

Ngy H

SH NCC

MtMH

VT

n gi

TnNCC

achNCC

th PTH lp t mt n hng

58

SH- H, MH

SH- H

SL t

MMH

Ngy H

SH NCC

MtMH

VT

n gi

TnNCC

achNCC

Ph ti thiu v cc quan h 3NF t n hng. 4. Xy dng biu cu trc d liu theo m hnh d liu quan h (Relational Data Model) M hnh d liu quan h (m hnh quan h) l m hnh d liu, trong s xc nh mt danh sch cc thuc tnh ca cc bng thc th Qui trnh thnh lp lc d liu cho h thng, theo m hnh quan h nh sau : (1) Thnh lp danh sch cc thuc tnh gi l danh sch xut pht . C th xem y l mt quan h, vi 1 ngh khi qut no , danh sch ny khng bao trm c cc d liu ca ton h thng, bi v qu trnh s cng c lp li vi nhiu danh sch xut pht khc nhau cho n khi vt cn cc thng tin cn thit cho h thng. C hai cch tip cn cho vic thnh lp danh sch xut pht : - Cch 1 : l tp hp cc thng tin c bn, pht hin c trong mt phm vi iu tra no , m ta xem l c ch cho cng tc qun l. - Cch 2 : Xut pht t 1 hay mt s ci ra ca h thng. Ci ra c th l : + Mt chng t hay mt ti liu in ra t h thng + Mn hnh trong giao tip ngi / my. (2) Tu sa li danh sch xut pht, qua cc cng vic sau: - Loi b cc tn ng ngha - Loi b cc thuc tnh tnh ton V d: Thnh tin = SLxDG Tng cng = Tng thnh tin - Truy nguyn cc thuc tnh dng tnh ton cc thuc tnh b loi trn nu chng cha c mt trong danh sch - Thay th cc thuc tnh khng n bi cc thuc tnh n.59

V d: C thuc tnh im Ton: thc cht y l mt dy kt qu thi ln1, ln2, ln3, ln4. (3) Tm ph thuc hm trong danh sch cc thuc tnh: - u tin l r cc kh nng c PTH gia tng cp cc thuc tnh trong danh sch. - Sau xt cc PTH c v tri gm 2, 3 .. thuc tnh (4) Tin hnh chun ho da trn tp cc PTH lp c trn, s dng 1 trong cc phng php chun ho bit. Kt qu thu c l tp cc lc 3NF. (5) Lp li cc bc t (1) n (4) cho cc danh sch xut pht khc nhau, cho n khi qut ht cc phm vi kho st. Ta c nhiu tp cc lc 3NF. (6) Ly hp cc kt qu thu c t cc ln lp trn. Khi ly hp nh vy, nu c 2 quan h c kho trng nhau, th chng ta gp thnh 1 quan h vi danh sch cc thuc tnh l hp ca hai danh sch tng ng 5. Xc nh mi quan h xy dng s E-R - Xy dng Ma trn thc th/kho: xc nh cc mi quan h trong m hnh ta lp bng ma trn thc th/kho trong : + Cc ct lit k cc tp thc th, cc hng lit k cc thuc tnh kho c trong cc tp thc th. + Tng ng vi mi giao gia ct v hng, nu: * Kho c trong tp thc th ta cho du X * Nu khng phi l kho nhng c xut hin trong tp thc th ta cho du O - Thit lp cc mi quan h: Cn c vo bng thc th/kho ta lit k cc mi quan h theo cch thc sau: Bt u t Tp thc th ct th nht, t cha kho ca n ta chiu qua cc k tip ca hng xem no c du X hoc O th ta s c mt lin kt ca Tp thc th ang xt vi tp thc th m c cha du trn cng mt hng. - Xy dng m hnh quan h V d: C 1 n hng bn ca mt cng ty nh sau:Cng ty XYZ S hiu:......... n hng bn Ngy:............... Tn khch hng:.............................................M s KH............... a ch:................................................................................................ M s MH Tn VT S lng n gi Thnh tin

60

Tng s tin: xxx xxx xxx

Kho st chn danh sch cc thuc tnh Tinh chnh cc thuc tnh. Xc nh cc ph thuc hm Thc hin qu trnh chun ho: n hng bn cha chun ho S hiu n M s KH Ngy t hng Tn KH a ch M s MH Tn VT S lng n gi Chun ho dng 1 Ta thy cc thuc tnh: M s MH Tn VT S lng n gi c th lp nhiu ln trong mt thc th n hng, do cn loi b v to ra tp thc th mi 1NF 2NF 3NF

61

n hng bn cha chun hoS hiu n M s KH Ngy t hng Tn KH a ch M s MH Tn VT S lng n gi

1NF# S hiu n M s KH Ngy t hng Tn KH a ch Tp thc th mi # S hiu n # M s MH Tn VT S lng n gi

2NF

3NF

Chun ho dng 2 Ta thy m t mt hng ch ph thuc hm vo M s MH ch khng ph thuc vo ton b kho l 2 thuc tnh ghp M s MH v S hiu n hng. Do ta lp thm tp thc th mi t tiu chun dng 2. n hng bn cha chun ho S hiu n M s KH Ngy t hng Tn KH a ch M s MH Tn VT S lng n gi 1NF # S hiu n M s KH Ngy t hng Tn KH a ch # S hiu n # M s MH Tn VT S lng n gi 2NF # S hiu n M s KH Ngy t hng Tn KH a ch # S hiu n # M s MH S lng # M s MH Tn VT n gi 3NF

Chun ho dng 3 Ta thy Tn KH v a ch KH ph thuc hm vo M s KH l thuc tnh khng phi l kho trong tp thc th, do chng ta a chng vo tp thc th mi m kho chnh l M s KH. n hng bn62

cha chun ho S hiu n M s KH Ngy t hng Tn KH a ch M s MH Tn VT S lng n gi

1NF #S hiu n M s KH Ngy t hng Tn KH a ch # S hiu n # M s MH Tn VT S lng n gi

2NF #S hiu n M s KH Ngy t hng Tn KH a ch # S hiu n # M s MH S lng # M s MH Tn n gi VT

3NF #S hiu n M s KH Ngy t hng #M s KH Tn KH a ch #S hiu n #M s MH S lng #M s MH Tn n gi VT

Sau khi chun ho dng 3, t n hng bn ta lp c 4 quan h chun ho 3NF l: n hng bn(S hiu n, M s KH, Ngy t hng) Khch hng(M s KH,Tn KH, a ch) Dng n hng(S hiu n, M s MH, S lng) Mt hng(M s MH, Tn, VT, n gi) Kt hp cc thng tin thu c: Gi s ta c 2 ti liu l n hng & Ti liu giao nhn hng c chun ho nh sau: n hng bn(S hiu n, M s KH, Ngy t hng) Khch hng(M s KH, Tn KH, a ch KH) Dng n hng(S hiu n, M s KH, S lng) Mt hng(M s MH, M t mt hng, n gi) Giao nhn(S hiu giao nhn, M s KH, Ngy giao, a ch giao nhn) Dng giao nhn(S hiu giao nhn, S hiu n, M s MH, s lng giao) Bc 4: Xc nh cc mi quan h Ma trn thc th/kho n hng S hiu n M s KH M s MH S hiu GN63

KH

Dng H X

Mt hng

Giao nhn X

Dng giao nhn X

X O X

X

X X

X X

Xy dng m hnh thc th lin kt:Khch hng n hng Mt hng

Giao nhn

Dng giao nhn

Dng n hng

6. M ho cc tn gi: 6.1. Khi nim m ho D liu dng trong h thng thng 2 dng s v dy k t (phi s). V ngha th dy k t l tn ca mt i tng no trong h thng. Ta gi m ho (codification) l vic gn mt tn gi vn tt (gi l m) cho mt i tng no . Cc i tng trong h thng c t tn c th l: Cc ng dng tin hc khc nhau trong doanh nghip. Cc chc nng. Cc n v x l. Cc chng trnh. Cc ti liu.p d liu. Cc thng tin trong cc ti liu v cc tp. Cc bin dng trong cc chng trnh... 6.2. Cht lng c bn ca m ho Vic m ho phi c gng t mt s yu cu v cht lng nh sau: - Khng nhp nhng: th hin nh x 1-1 t tp cc i tng v tp cc m. - Thch hp vi phng thc s dng: S dng cho ngi: m phi d hiu, d gii m. S dng cho my tnh: m phi c nh ngha mt cch cht ch. - C kh nng m rng v xen thm: M rng: b sung pha trn v pha di. Xen thm: b sung trong mt th t. thc hin kh nng xen thm c th dng 2 cch:64

Nhy cc theo mt gi tr nht nh. Nhy cc theo mt kt qu thng k. - Phi ngn gn, bi v m cng di th vic x l cng thm kh khn. Tuy nhin, chiu di ca m li nh hng ti kh nng m rng m. V d: Vi m l 4 con s th nhiu nht c th ch nh 9999 i tng. - C tnh gi (din ngha): nhn m, con ngi c th d on ra i tng. Chng hn m ho cc thnh ph th: H Ni c gn m 29 (trong bin s xe) l km gi . Tri li, trong ngnh hng khng, ngi ta ch cn dng ba ch ci ch nh cc thnh ph, m vn giu tnh din ngha: H Ni c m l HAN

Bng cc ---------- BKK Bombay ----------- BOM 6.3. Cc kiu m ho khc nhau (1) M ho lin tip: - Dng cc s lin tip ch cc i tng V d: M ho cc khch hng theo th t thi gian: 001, 002, ...084,... - u im: Khng nhp nhng (nu khng hn ch v di). n gin. M rng pha sau c (nu khng hn ch v di). - Khuyt im: Khng xen thm c. Khng gi , vy phi c mt bng tng ng m v i tng, Khng phn nhm. (2) M ho theo lt: Dng tng lt cho tng i tng. Trong mi lt, thng dng kiu m ho lin tip. V d: cc i tng l cc hng ng kim: 0001 - 0999: hng ng kim b, trong : 0001 - 0099 : cc loi vt65

0100 - 0299 : cc loi -cu. 0300 - 0499 : cc loi bu-long 1000-1999: cc chi tit bng kim loi, trong : 1000 -1099 : cc st ch U. - u im: Khng nhp nhng (nu cc lt l tch ri, tc l khng c i tng thuc vo 2 lt khc nhau). n gin. M rng v xen thm c. - Khuyt im: Vn dng bng tng ng. (3) M ho phn on M c phn thnh nhiu on, mi on mang mt ngha ring. V d: S ng k xe my: 99 AA 999 S hiu lin tip Cc ch tr lt S hiu tr tnh, thnh S bo him x hi cho tng c nhn: 9 99 99 99 99 999 999 S ng k trong phng Phng x} Qun, huyn Tnh thnh Nm } Thng Gii tnh - u im: Khng nhp nhng. M rng v xen thm c (nu mi on cn ch). Dng ph bin. Cho php thit lp cc kim tra gin tip (V d: s bo him c khp vi cc thng tin tng ng ghi trong chng minh th khng?). - Khuyt im:66

Ni

Ngy sinh

Thng qu di. Thao tc nng n khi m c qu nhiu on. Vn c th b bo ho. M khng c nh (v d i ni th phi i s bo him). (4) M ho phn cp: Cng l phn on, song mi on tr mt tp hp cc i tng v cc tp hp bao nhau theo th t t tri qua phi. V d: nh s cc mc trong mt cun sch 9 9 9 S th t mc trong tit

S th t tit trong chng S th t chng (5) M ho din ngha: Gn mt tn ngn gn, nhng hiu c cho tng i tng. V d: #MANS: L m s cn b trong c quan. u im: Tin dng cho x l th cng. Khuyt im: Khng gii m c bng my tnh. 7. T in d liu 7.1. Khi nim: T in d liu l mt t liu tp trung v mi tn gi ca mi i tng c dng trong h thng trong c cc giai on phn tch, thit k, ci t, bo tr. Chng hn + mc logic, c: cc lung d liu, cc giao dch, cc s kin, cc chc nng x l, cc thc th, cc thuc tnh, ... + mc vt l: cc tp, cc chng tnh, cc chng trnh con, cc modun, th tc, ... T in d liu l cn thit c bit cho qu trnh trin khai cc h thng ln, c ng ngi tham gia. N cho php: + Trong PT v TK: qun l tp trung v chnh xc mi thut ng v cc m dng trong h thng, kim sot c s trng lp, ng ngha hay ng m d ngha, ... + Trong ci t: ngi ci t hiu c chnh xc cc thut ng t kt qu PTTK

67

+ Trong bo tr: khi cn thay i, th pht hin c cc mi lin quan, cc nh hng c th ny sinh. T in d liu : l mt tp hp cc mc t, mi mc t tng ng vi mt tn gi km vi gii thch i vi n. 7.2. Cc hnh thc thc hin t in: - Bng tay: l mt tp ti liu - Bng my tnh: dng 1 h phn mm cho php d dng thnh lp, thay i 7.3. Cu to t in: K php m t ni dung cho t in d liu tun theo bng sau: Kt cu d liu Tun t Tuyn chn Lp K php = + [|] { }n () * Li ch thch * ngha c to t v hoc lp n ln d liu tu chn gii hn ch thch

V d: t ho n bn hng sau: HO N BN HNG S ho n: 135 Ngy bn: 10 11 2006 Bn cho ng / b: L Hoi Nam Ti khon: LTM010254 a ch: 354 Phan nh Phng Tel: (0280) 756350 M hng Tn VT n gi S lng Thnh tin X30 Tng cng: Bng ch: K ton trng Ta c mt phn t in sau: * Xc nh mt t ho n nh sau * Ho n = S H + Ngy bn + Khch hng + + Tng cng + KT trng + Ngi bn * Xc nh thng tin v khch hng *68

STT 1 ....

Ghi ch

Ngi np tin

Ngi bn hng

+ Hng + S lng + Thnh tin

n

Khch hng = H tn khch + Ti khon + a ch + in thoi * Xc nh thng tin v tng mt hng * Hng = M hng + Tn + VT + n gi

69

Chng 6: Thit k h thngTng quan v giai on thit k Xut pht: u vo ca giai on ny bao gm biu phn cp chc nng, biu lung d liu v biu cu trc d liu. Nhim v: Nhim v ca giai on ny l chuyn cc m t mc khi nim ca h thng mi thnh m t vt l bng cch b sung tr li cc bin php, cc phng tin (b sung li cc yu t vt l) Tin hnh: C th phn chia thnh 5 bc Bc 1: Thit k tng th, trong bc ny c tch thnh 2 bc nh Bc 2: Thit k cc m un x l Bc 3 Thit k giao din Bc 4: Thit k cc kim sot Bc 5: Thit k cc tp 1. Thit k tng th 1.1. Phn nh ranh gii gia chc nng my tnh v chc nng th cng - D liu u vo ca phn ny l biu lung d liu mc no , ti liu ra (u ra) vn l biu nhng c phn nh r ranh gii gia my tnh v th cng. - Cch thc hin nh sau: a) i vi cc chc nng x l: Vi cc chc nng nm hn v 1 bn hoc l th cng hoc l my tnh th gi nguyn, cn vi nhng chc nng cha phn nh r c th xy ra mt trong hai kh nng: - Cn c vo tnh hnh mc tin hc ho chuyn sang thc hin trn my tnh hon ton; hoc chuyn sang lm th cng hon ton - Phn r tip thnh mt s chc nng cho n khi chc nng mi c xc nh l chc nng th cng hay chc nng ca my tnh. b) i viH cung cp liu: cc kho dNh CC/MH NCC

- Vi cc kho nm vng th cng (c th ch cc h s chng t vn phng) phi i B sung chiu vi biu cu trc d liu loi b thc th tng ng vi kho d liu ny.NCC

Cho hng

Nh CC hp ng VD: Tr li bi ton cung ng vt t vi chc nng l chn ngun cung cp NCC c chn

Chn

Hp ng mi

- i vi kho d liu nm trong vng my tnh thng n s l cc tp tin phi i chiu li vi biu cu trc d liu b sung thm thc th tng ng vi n (nu thiu) LmCC

Thng lng

Yu cu CC

70

Yu cu CC

Ngi CC

Trong 2 chc nng trn u c phn va th cng va my tnh nn tin hnh phn r tip nh sau:H cung cp Nh CC/MH NCC

Tra cu cc H c 1.2

Tra cu v NCC 1.3

Ghi nhn NCC mi 2.2

Ghi nhn H mi 2.3

MT TCTm NCC 1.1 TT cho hng NCC c chn Thng lng H 2.1

Yu cu TT cho hng

H mi

Ch : Trong v d ny vic phn r ch mang tnh cht minh tit thng phn r phi Chi ho. Vic Nh CC lng da vo quy trnh x l c th trong tng giai on. 1.2. Phn nh cc h thng con ca my tnh - Mc ch: Xy dng c cc b chng trnh ng gi (packet), mi gi tng ng vi h thng con trong h thng. Cn c vo cc chc nng ca h thng trong cc biu phn r. - Cch thc hin: Dng cc ng gch ni khoanh tng vng ng vi cc chc nng lin quan n nhau trong vic x l. Ngoi ra c mt s cn c sau:71

a) Theo kiu thc th Gom t cc chc nng c lin quan n mt kiu thc th hay mt nhm thc th (c th l 1 tp). V d h thng con khch hng bao gm cc chc nng lin quan n thc th khch hng (v d: chc nng chn NCC, lp n hng, tr li thng lng vi khch hng... l mt nhm. Cc chc nng v qun l kho vt t lin quan n thc th kho hng bao gm cc chc nng nhp hng, xut hng, bo co tn... vo mt nhm) b) Theo giao dch Gom t theo giao dch: Cn c vo lung d liu, khi t mi trng bn ngoi vo s kch hot 1 lot cc chc nng ca h thng. VD: Khi c yu cu d tr vt t th nhng chc nng lin quan khch hng u b kch hot. c) Theo trung tm bin i Quan st trn biu lung d liu, nu pht hin c c 1 khu vc tp trung x l cc thng tin ch yu th gom nhng chc nng ny li. VD: Chc nng lm bng lng s ko theo cc chc nng nhp bng chm cng, nhp nh mc lng, chc nng in n cc biu lng. d) Theo tnh thit thc Theo cu trc kinh doanh ca c quan, theo v tr c s, theo trnh i ng, trch nhim cng tc (phn quyn) VD: Gim c c th xem bo co nhng gim c khng sa c. *Ch : Khi khoanh vng gia cc vng c th xy ra trng hp l cc vng khng lin thng vi nhau khi h thng s c nhiu chng trnh con tch ri. Nu cc my tnh trong h thng c ni mng ta c th t chc thnh CSDL chung c th lin thng vi nhau. 2. Thit k chi tit v cc th tc th cng v v cc giao tip ngi - my 2.1. Cc chc nng th cng - Hnh ng ra quyt nh: Con ngi lm ch h thng nn mi quyt nh u do con ngi thc hin, my tnh ch c th cung cp thng tin tr gip - Hot ng giao tip gia con ngi v con ngi: S trao i vi cc tc nhn ngoi h thng (i tc kinh doanh, cc b phn tc nghip...) - Cc nhim v phc v cho my tnh - Cc chc nng th cng bao gm m ho thng tin, kim sot, sa cha thng tin, nhp thng tin, kim tra v phn phi ti liu xut. Cc chc nng ny c nhiu loi: C loi khng lin quan n my tnh C s tr gip ca my tnh 2 ch Online hoc Offline. L nhng chc nng th cng "n theo" hay ni cch khc l nhng chc nng pht sinh do vic s dng my tnh.72

- Khi s l cc chc nng th cng phi ch r ni dung cng vic phi lm theo khng gian v thi gian, c bit l khi pha trn gia my tnh v th cng, yu cu v nng sut cht lng, k nng, quy trnh thc hin, cc cch x l khi gp sai st. 2.2. Thit k u vo ca thng tin a) Chn phng thc thu thp thng tin - Phng thc trc tuyn - Phng thc theo m - Phng thc thu thp t xa qua cm bin b) K thut iu tra thu thp thng tin -Dng mu iu tra: Dng thu thp thng tin, ngi c hi in vo mu c sn. Mu thng chia lm 3 phn: Phn u: L tiu Phn ni dung: Chi tit thng tin cn iu tra Phn cam oan Phn k tn Mt sau phiu l cc hng dn tr li, cch in vo cc mc trong phiu - Dng cu hi (c hai loi cu hi ng, cu hi m): Cu hi ng l nhng cu hi m cc phng n tr li l c a ra sn; cu hi m l nhng cu hi mang tnh cht gi , cn phi phi hp nhiu cu hi mi xc nh c ng thng tin cn thit. c) Yu cu vic thu thp thng tin - Thun tin cho ngi iu tra - Thun tin cho vic m ho - Thun tin cho vic g phm - Ni dung n gin, r rng, chnh xc... 3. Thit k cc ti liu xut -Yu cu i vi cc ti liu xut l phi thng tin theo yu cu v phi chnh xc, d hiu, d c. - Cc phng thc xut thng tin: a ra my in a ra mn hnh a ra b nh ngoi a ra cc xung iu khin -Cc ti liu xut bao gm cc loi sau: - Thng tin tu tin khng c chun trc. Nhng thng tin ny thng di dng l kt qu ca cc truy vn v l mt trong nhng nhu cu tng i ph dng trong cc bi ton qun l. - Cc ti liu in c cc mu biu theo tiu chun. Cc hnh thc a ra:73

+ C khung in sn + Khng c khung in sn - V cch trnh by mt biu nh sau: + u biu: tn ca biu + Thn biu: bao gm cc ni dung c bn v cc nhm logic quan h vi nhau + Cui biu: VD: H ni, ngy... thng....nm...

2.4. Thit k mn hnh chn - Mc ch s dng mn hnh: Dng i thoi Ngi My s dng trong i thoi c c im: + Thng tin thng l ti thiu + Vo ra gn nhau (dng hi - p) - Yu cu v mt thit k + C tnh m thut, thn thin, d nhn, d hiu + Biu din cu lnh ngn gn ch c cc thng tin ti thiu - Hnh thc i thoi trn mn hnh + Dng thc n chn (menu): cp 1, cp 2, cp 3 + Dng cu lnh, du nhc + Dng in mu (form) + Dng hp chn, nt iu khin, danh sch chn ... - S dng a phng tin v d nh: m thanh, cc thit b im lm sinh ng trong giao tip ngi my. 3. Thit k chng trnh 3.1.i cng -Mc ch: Xc nh tng quan chng trnh v phn nh cc m un chuyn cho cc lp trnh vin ci t chng trnh74

-Ni dung: Phn nh cc m un. Xc nh mi quan h gia cc m un (vic trao i thng tin, gi nhau trong chng trnh chnh). c t tng m un: xc nh cc bin, cc thut ton, cc d liu c x l, cc chc nng x l. Cch ghp ni cc m un. Thit k cc mu th ring cho tng m un -Phng php: Thit k theo phng php Topdown lm mn dn cc m un. S dng lc cu trc 3.2. Cc m un chng trnh - Chng trnh bin tp - Chng trnh nhp - Chng trnh cp nht - Chng trnh hin th - Chng trnh tnh ton - Chng trnh to menu - Chng trnh in -Mi m un c th l mt chng trnh con, cng c th l mt on lnh. Mi m un c nhng c trng sau: (1)- Ci vo, ra: Nhng thng tin ca m un khc truyn cho n; thng tin n truyn cho cc m un khc (2)-Chc nng: Th hin vic bin i ci vo thnh ci ra (3)-C ch thc hin: Cc thut ton dng trong m un (4)-D liu cc b: D liu ring ca m un c th ch sinh ra tm thi trong b nh trong khi hon thnh nhim v s b xo i. c trng 1, 2 gi l c trng ngoi, 3, 4 gi l c trng trong, ngoi ra cn cc c trng ph nh tn, v tr ca m un... -Khi thit k chng trnh trc ht ta phi m t cu trc chng trnh theo cc m un da trn cc c trng ngoi, sau chi tit ho cc m un (Topdown) - m t cu trc chng trnh ta dng lc cu trc (LCT) 3.3. Lc cu trc -Biu din m un: Dng hnh ch nht bn trong c tn m un, m un c sn dng hnh CN c hai vch hai cnh bn:

-Biu din cc lin kt: Dng on thng c hng, nu gi nhiu ln c thm cung trn: (A gi B; A gi C nhiu ln)75

A

B

A

C

-Cu trc gi c la chn: A gi B hoc C

A

B

C

- Biu din lung thng tin V d: M un tnh lng

tnh lngBc L. chnh L. chnh P. cp

L. chnh P. cp

tnh L. chnh L. chnh P. cp

tnh P. cp

in b. lng

3.4. nh gi v lc

PC cho NV trong Bin ch cu trc

PC cho NV hp ng di hn

PC cho NV hp ng ngn hn

-S tng tc: Ni ln s nh hng ln nhau gia cc m un, cc m un cng t nh hng nhau cng tt, m bo s c lp gia cc m un. C cc s tng tc sau: -M un ny can thip vo m un kia, tng tc ny khng tt cn loi b. -Tng tc v iu kin: m un ny chuyn thng tin iu kin cho m un kia, phi hiu ni b m un kia cn iu kin g nh vy vi phm tnh che du ca m un m thng thng mi m un l mt hp kn. Do tng tc ny khng tt -Tng tc v d liu: Tng tc cng n gin cng tt, thng dng tham tr, hn ch dng tham bin, nn truyn theo d liu hn l dng con tr. - S cu kt: Phn nh s gn b v mt l gc ca cc b phn trong m un -Hnh thc: Biu hin cu trc b ngoi ca LCT c dng Topdown76

-Phm vi iu khin: L vai tr quyt nh ca m un ny vi m un khc mnh hay yu khc nhau gia cc m un. 3.5. Chuyn BLD thnh LCT -Nguyn tc: -Phi tinh ch BLD trc khi chuyn -Ch cc chc nng chnh yu trc cc chc nng ph sau -Ngoi cc chc nng trong BLD cn c thm cc m un vo ra 5.1-Phng phng php phn tch theo bin i (1) Di theo cc dng d liu vo cho n khi d liu vo tr thnh tru tng nht hoc gp mt thit b, mt kho m d liu c coi l d liu vo th nh du li. (2). Lm ngc li vi thng tin ra. (3) Cn c vo cc im nh du khoanh li mt vng ca BLD ta lp mt LCT (4) u tin v mc cao nht l m un chnh mi dng vo l mt m un vo, mi dng ra l mt m un ra (5) Trin khai tip trong cu trc s xut hin nhng m un gia thc hin cc chc nng bin i trong m un chnh -V d:

Ngun X

x1

A

x2

B

x3

C x4 G y4

q1

H

q3 J

s1

K

s2

L

Ngun Y

y1

A y2 D

E

y3

F

q2

I

q4

VoLy x4

bin i Bin i RAG

Ra

Vox4

Ly y4 x3 Ly x3 x2 Ly x2 x1 Ly x1

Cx3

G

G

Bx2

J

A

77 Ngun x

x4 y4 4

4

4 4q1

s 1

to s1 q2 q3q4

H 5.2-Phng phng php phn tch theo giao dch

I

Qu trnh hnh thnh h thng con thng qua giao dch. Ta quan tm n nhng thng tin theo lung trong BLD n khi n kch hot cc chc nng khc th dng li lp LCT cho h thng con ny. V d:n hng 4. Thit k c s d liu H hp l

4. 1. Mc ch

Phn loi

H khng hp l H khng p

- C s d liu l ni lu tr lu di cc d liu ca h thng b nh ngoi. Cc d ng liu ny phi c t chc tt theo hai tiu ch: Hp l: ngha l phi dng v khng d tha Truy nhp thun li: ngha l tm kim, cp nht, b sung v loi b cc thng tin sao cho nhanh chng v tin dng. - giai on phn tch, ta nghin cu d liu theo tiu ch hp l ( v khng d tha). Kt qu l thnh lp c lc d liu theo m hnh thc th lin kt hay m hnh quan h. Thng c gi l lc khi nim v d liu, v n dng li yu cu v khng tha, m b qua yu cu nhanh v tin. - Sang giai on thit k, ta phi bin i lc khi nim ni trn thnh lc vt l, tc l mt cu trc lu tr thc s ca d liu b nh ngoi.78

- Ngi ta thng tch vic thit k d liu thnh hai bc: (i) Thng qua vic nghin cu cc yu cu truy nhp m bin i lc khi nim thnh mt dng trung gian gi l lc logic v d liu: Qui tc chuyn cc kiu thc th: + Tn thc th -> Tn quan h + Thuc tnh ca thc th -> thuc tnh ca quan h + Thuc tnh kho -> kho ca quan h Qui tc chun ho cc quan h: Bng vi nhm lp Tch nhm lp Chun 1, cha chun 2 Tch ph thuc vo 1 phn kho Tch ph thuc bc cu Chun 3 Hp nht cc quan h: Loi cc quan h tha

Chun 2, cha chun 3

- Ch : S ng ngha, S ng danh, S ph thuc bc cuQui trnh thit k: Chuyn cc m hnh thc th sang m hnh quan h Xc nh kho v chun ho cc quan h nhn c

- Tch hp cc quan h nhn cV biu m hnh d liu quan h v xc nh cc lc lng tham gia vo quan h (ii) Thng qua vic nghin cu cc cu hnh ca h thng, c bit l cc ngn ng lp trnh, cc h qun tr CSDL c chn dng m bin i lc logic thnh lc vt l thch hp vi cu hnh . 4.2. Thnh lp lc logic 4.2.1. Lc logic:

79

Mi cu trc lu tr vt l, d l tp hay CSDL th cng u to nn t cc n v c s l cc bn ghi. V vy ngi ta chn lc logic, mt dng trung gian trc khi n lc vt l, l mt cu trc kiu bn ghi. Mi kiu bn ghi l mt tp hp nhng bn ghi c cu trc trng ging nhau, thng c gi cho gn l mt bng. Bng c biu din bng mt hnh ch nht c tn bng (vit bn ngoi), danh sch cc trng (vit bn trong). Gia 2 bng thit lp mt mi lin kt din t bng 1 mi tn, nu hai bng c mt trng chung. Tn trng ny c ly lm nhn cho kt ni V d: c gi S th G Tn c gi a ch Trnh Mn S th G M sch Ngy mn Ngy tr Sch M sch Tn sch Tn tc gi NXB

Bc thit k logic xut pht t mt lc khi nim v d liu di dng m hnh quan h chun ho (v 3NF). trong mi quan h tr thnh mt kiu bn ghi, cn cc kt ni s c thm vo khi c mt cc kho ngoi. Mc ch ca thit k logic l xut pht t lc khi nim ta i tm mt cu trc kiu bn ghi ph hp vi cc yu cu truy nhp ca cc chc nng x l trong h thng. Chnh v vy vic thit k logic c xu hng git li so vi qu trnh phn tch: chp nhn s d tha, c th h chun, min l s li/hi ca bc git li ny l c cn nhc rt cn thn. 4.