•By: Meadow Heath

FOCUS to DB2

• Define DB2 table to FOCUS

• How FOCUS processes a DB2 request

• FOCUS to DB2 Efficiencies

Define DB2 table to FOCUS

• CAR Master File Description

• CAR Access File Description

CAR MFDFILE=CAR ,SUFFIX=SQLDS ,$ SEGNAME=CAR ,SEGTYPE=S0 ,$ FIELD=COUNTRY ,COUNTRY ,A10 ,A10 ,MISSING=OFF,$ FIELD=CAR ,CARS ,A16 ,A16 ,MISSING=OFF,$ FIELD=MODEL ,MODEL ,A24 ,A24 ,MISSING=OFF,$ FIELD=BODYTYPE ,TYPE ,A12 ,A12 ,MISSING=OFF,$ FIELD=SEATS ,SEAT ,I3 ,I4 ,MISSING=OFF,$ FIELD=DEALER_COST ,DCOST ,D7 ,D8 ,MISSING=OFF,$ FIELD=RETAIL_COST ,RCOST ,D7 ,D8 ,MISSING=OFF,$ FIELD=SALES ,UNITS ,I6 ,I4 ,MISSING=OFF,$ FIELD=LENGTH ,LEN ,D5 ,D5 ,MISSING=OFF,$ FIELD=WIDTH ,WIDTH ,D5 ,D5 ,MISSING=OFF,$ FIELD=HEIGHT ,HEIGHT ,A2 ,A2 ,MISSING=OFF,$ FIELD=WHEELBASE ,BASE ,D6.1 ,D8 ,MISSING=OFF,$ FIELD=FUEL_CAP ,FUEL ,D6.1 ,D8 ,MISSING=OFF,$ FIELD=BHP ,POWER ,D6 ,D6 ,MISSING=OFF,$ FIELD=RPM ,RPM ,I5 ,I4 ,MISSING=OFF,$

ALIAS column should be the same name as the column name defined to the DB2 table

MISSING = OFF default value and should be used with NOT NULL columns in DB2MISSING = ON displays the FOCUS NODATA value for missing data

ACTUAL format is converted from the SQL Datatype: CHAR(n)=An, VARCHAR(n)=An, SMALLINT=I4, INTEGER=I4, DECIMAL=P, REAL=F4, FLOAT=D8,DATE=DATE . . .

CAR ACCESS File

SEGNAME= CAR ,TABLENAME= '”IBI".”CAR"' ,KEYS= 0 ,WRITE= YES ,$

SEGMENT associates the Master File with table it describes

WRITE=YES (default) specifies read and write access using MODIFY and MAINTAIN

WRITE=NO Read-only access using MODIFY and MAINTAIN

PRIMARY KEY must be defined (if there is one)

KYFLD and IXFLD would be included for multi-table structures -- used for dynamic JOINs.

ALLOCATION for the Access File is done in the FOCSQL libraryDYNAM ALLOC FILE FOCSQL DA {node}.FOCSQL.DATA

FOCUS to DB2 Processing

• High level diagram of process– FOCUS Request– DB2 Interface– Results

FOCUS Request

Programmer submits a FOCEXEC:

TABLE FILE CAR PRINT CAR MODEL DEALER_COST RETAIL_COST END

High Level Diagram of Process

FOCUS(Processing)

DB2Interface

(creates SQL) db2 request focexec

• Programmer executes FOCEXEC

• FOCUS parses request and passes to DB2 Interface

DB2 Interface

DB2 Interface translates the FOCEXECinto SQL code:

TABLE FILE CAR PRINT CAR MODEL DEALER_COST RETAIL_COST END

SQL:SELECT T1.CAR,T1.MODEL,T1.DCOST,T1.RCOST FROM CAR T1 FOR FETCH ONLY;

High Level Diagram of Process

FOCUS(Processing)

DB2Interface

(creates SQL)

RDBMS

Table Table

db2 request focexec

db2 results

sql

data • FOCUS parses request and passes to DB2 Interface

• DB2 Interface builds SQL & passes to RDBMS

• RDBMS retrieves data from DB2 table(s)

• RDBMS returns data to DB2 Interface

• FOCUS completes any process not handled by DB2

• Programmer executes FOCEXEC

results

• Results returned to programmer

Results

FOCEXEC:TABLE FILE CAR PRINT CAR MODEL DEALER_COST RETAIL_COST END

SQL:SELECT T1.CAR,T1.MODEL,T1.DCOST,T2RCOST FROM CAR T1 FOR FETCH ONLY;

RESULTS:CAR MODEL DEALER_COST RETAIL_COST--- ----- ----------- -----------JAGUAR V12XKE AUTO 7,427 8,878JAGUAR XJ12L AUTO 11,194 13,491JENSEN INTERCEPTOR III 14,940 17,850DATSUN B210 2 DOOR AUTO 2,626 3,139MASERATI DORA 2 DOOR 25,000 31,500...PEUGEOT 504 4 DOOR 4,631 5,610

FOCUS to DB2 Efficiencies

• Sorting Data

• Selection Criteria

• Data Calculations

• How to determine efficiency

Sorting Data

• Sorting Defined field

• Sorting on DB2 field

Sorting on Define fieldFOCEXEC:DEFINE FILE CAR NEW_NAME/A3 =EDIT(MODEL,'999'); END TABLE FILE CAR PRINT CAR BY NEW_NAME END

SQL:SELECT T1.CAR,T1.MODEL FROM CAR T1 FOR FETCH ONLY;

RESULTS:NEW_NAME CAR -------- --- B21 DATSUN COR TOYOTA DOR MASERATI ...530 BMW

NOTICE: Sort statement is not passed to DB2; FOCUS will have to sort the data before sending results back to the programmer.

Sorting on DB2 fieldFOCEXEC:DEFINE FILE CAR NEW_NAME/A3 =EDIT(MODEL,'999'); END TABLE FILE CAR PRINT NEW_NAME CAR BY MODEL NOPRINT END

SQL:SELECT T1.CAR,T1.MODEL FROM CAR T1 ORDER BY T1.MODEL FOR FETCH ONLY;

RESULTS:NEW_NAME CAR -------- --- B21 DATSUN COR TOYOTA DOR MASERATI ...530 BMW

NOTICE: ORDER BY statement is added to the SQL passed to DB2. DB2 will sort the data before returning results to FOCUS.

Selection Criteria

• Selecting from fields created with User-written subroutines

• Selecting from fields created with Edit feature

Selecting from fields created with User-written subroutines

FOCEXEC:DEFINE FILE CAR NEW_NAME/A3 =SUBSTR(24,MODEL,1,3,3,NEW_NAME); END TABLE FILE CAR PRINT CAR BY NEW_NAME WHERE NEW_NAME LT 'C' END

SQL:SELECT T1.CAR,T1.MODEL FROM CAR T1 FOR FETCH ONLY;

RESULTS:NEW_NAME CAR -------- --- B21 DATSUN

NOTICE: No selection criteria is passed to DB2; therefore, DB2 will pass all the data back, and FOCUS will have to complete the request.

Selecting from fields created with Edit Feature

FOCEXEC:DEFINE FILE CAR NEW_NAME/A3 =EDIT(MODEL,'999'); END TABLE FILE CAR PRINT CAR BY NEW_NAME WHERE NEW_NAME LT 'C' END

SQL:SELECT T1.CAR,T1.MODEL FROM CAR T1 WHERE ((SUBSTR(T1.MODEL,1,3)) < ‘C’) FOR FETCH ONLY;

RESULTS:NEW_NAME CAR -------- --- B21 DATSUN

NOTICE: WHERE NEW_NAME LT ‘C’ is translated by the DB2 Interface.

Data Calculations

• Calculations in a Compute

• Calculations in a Define

Calculations with ComputeFOCEXEC:TABLE FILE CAR SUM COMPUTE NEW_AMT/D7 =RETAIL_COST - DEALER_COST; BY CAR END

SQL:SELECT T1.CAR,SUM(T1.DCOST),SUM(T1.RCOST) FROM CAR T1 GROUP BY T1.CAR ORDER T1.CAR FOR FETCH ONLY;

RESULTS:CAR NEW_AMT --- ------- ALFA ROMEO 3,330 AUDI 907 BMW 9,262 DATSUN 513 JAGUAR 3,748 JENSEN 2,910 MASERATI 6,500 PEUGEOT 979 TOYOTA 453 TRIUMPH 808

NOTICE: NEW_AMT is not translated by the DB2 Interface; therefore, FOCUS does this calculation once all the data is retrieved from DB2.

Calculations in DefineFOCEXEC:DEFINE FILE CAR NEW_AMT/D7 =RETAIL_COST - DEALER_COST; END TABLE FILE CAR SUM NEW_AMT BY CAR END

SQL:SELECT T1.CAR, SUM((T1.RCOST - T1.DCOST)) FROM CAR T1GROUP BY T1.CAR ORDER BY T1.CAR FOR FETCH ONLY;

RESULTS:CAR NEW_AMT --- ------- ALFA ROMEO 3,330 AUDI 907 BMW 9,262 ..TRIUMPH 808

NOTICE: NEW_AMT is passed to DB2 to do the calculation.

How to determine efficiency

Test efficiency with FSTRACE4

FSTRACE4 shows the translation into SQL code

1) DYNAM ALLOC FILE FSTRACE4 *

(OR ALLOCATE TO A FILE)

2) Execute your FOCEXEC

3) Review FSTRACE4 to verify that the DB2 Translator converted your FOCEXEC into SQL code where possible

Summary

• Define DB2 table to FOCUS in the Master File Description and Access File Description

Define the DB2 table to FOCUS

Master File Description (MASTER)

FILE=CAR ,SUFFIX=SQLDS ,$ SEGNAME=CAR ,SEGTYPE=S0 ,$ FIELD=COUNTRY ,COUNTRY ,A10 ,A10 ,MISSING=OFF,$ FIELD=CAR ,CARS ,A16 ,A16 ,MISSING=OFF,$ FIELD=MODEL ,MODEL ,A24 ,A24 ,MISSING=OFF,$ . . . FIELD=RPM ,RPM ,I5 ,I4 ,MISSING=OFF,$

Access File Description (FOCSQL)

SEGNAME= CAR ,TABLENAME= '”IBI".”CAR"' ,KEYS= 0 ,WRITE= YES ,$

Summary

• Define DB2 table to FOCUS in the Master File Description and Access File Description

• The DB2 Translator translates the FOCEXEC into SQL code to be passed to the RDBMS

High Level Diagram of Process

FOCUS(Processing)

DB2Interface

(creates SQL)

RDBMS

Table Table

db2 request focexec

db2 results

sql

data • FOCUS parses request and passes to DB2 Interface

• DB2 Interface builds SQL & passes to RDBMS

• RDBMS retrieves data from DB2 table(s)

• RDBMS returns data to DB2 Interface

• FOCUS completes any process not handled by DB2

• Programmer executes FOCEXEC

results

• Results returned to programmer

Summary

• Define DB2 table to FOCUS in the Master File Description and Access File Description

• The DB2 Translator translates the FOCEXEC into SQL code to be passed to the RDBMS

• Write your FOCEXEC to be more efficient by making DB2 do most of the work

DB2 should do most of the work

• DB2 Translator should be able to convert your data processing into SQL code when:– Sorting Data – Selection Criteria– Data Calculations

• Test efficiency with FSTRACE4

Questions