INTRODUCTION TO ORACLE Lynnwood Brown System Managers LLC Application Development For DBA’s...

INTRODUCTION TO ORACLE

Lynnwood Brown

System Managers LLC

Application Development For DBA’s Lecture 8

Copyright System Managers LLC 2007 all rights reserved.

APPLICATION DEVELOPEMENT

Entity-Relationship Modeling

The ER model provides the framework for understanding how the application should be written.

• Models can be changed quickly

• Models show the alternatives to satisfying a business requirement

• Model can be used to estimate system capacity requirements

APPLICATION DEVELOPEMENT

ER modeling is a graphical technique for capturing business information and the relationships between the data. ER models consist of:

Entities - The things of significance about the information that is held. Entities often become the tables or views that a application will use

Relationships - Describe how the entities Rae related. The different types of relationships include one to one (1:1), one to many (1:M), many to one (M:1), many to many (M:M) and optional relationships.

Attributes - The specific information that describes the entity. Attributes often become the columns in the tables. An attribute can be mandatory (must always have a value - *), optional (can be NULL - o) or unique (#).

APPLICATION DEVELOPMENTER Model Components

E N T IT Y

one to one one to m any m any to m any

Type s of re la tio nship s:

- - - - - - - - - -op tional


APPLICATION DEVELOPMENT One To One Relationships

Computer Motherboard- - - - - - -

Each computer must have one motherboard

Each motherboard may be put into one computer


APPLICATION DEVELOPMENTOne To Many Relationships

S ales Representat ive Custom er- - - - - -

Each customer must be visited by only one sales representative.

A sales representative may be assigned one or more customers.


APPLICATION DEVELOPMENT

My name is K.E. Nell. I am the owner and operator of KEN’s Kennel. At KEN’s Kennel we board pets while their owners are out of town. When the owner brings in their pet we obtain the name of the owner, the name of each pet, the age f each pet and the pets weight, species, gender, color and breed.

We also need information about the customer. We need their name, address,

home phone, their veterinarian’s name and phone number, and when they will be returning for the pet.

Each pet, I house in a very spacious kennel suite during his or her stay. The

larger pets reside in a 30 x 20 foot kennel and the smaller pets get a nice cozy 10 x 5 foot kennel suite. For the pets safety and comfort only one pet is placed into a kennel suite at a time.



In the narrative we must first find the entities or “things of significance”. The characteristics of an entity include:

• An entity is an object of interest/significance to the business

• An entity is a noun• An entity is a category or class


APPLICATION DEVELOPMENTER Model

Pe t#* ido ageo w e igh t* s pec ieso breedo c o lo ro g ender

Ke nn e l#* loc a tion* s iz e

Ow n e r#* id* name* p hone* v e ter inar ian name* v e ter inar ian p hone* re turn da te

- - - - - -- -


APPLICATION DEVELOPMENTImplementing Business Rules

Business rules are implemented by using constraints. The different types of constraints include:

Primary Key Constraint – All column values must be unique and not null

Unique Constraint – All column values must be unique

Not Null Constraint – No column data can contain a NULL (a value must be supplied)

Foreign Key Constraint – The values of the column data in one table (child) must first exist in another table (parent)



Creating a primary key constraint Creating a primary key constraint at table creation time: SQL > CREATE TABLE EMP(EMPNO NUMBER PRIMARY KEY,ENAME VARCHAR2(20),…..); Creating a primary key constraint after the table has been created: SQL > ALTER TABLE EMP ADD PRIMARY KEY (EMPNO);



Creating a unique constraint Creating a unique constraint at table creation time: SQL > CREATE TABLE EMP(DEPTNO NUMBER,DEPT_NAME VARCHAR2(10) CONSTRAINT UN_NAME

UNIQUE,…); Creating a unique constraint after the table has been created: SQL > CREATE UNIQUE INDEX ON DEPT (DEPT_NAME);



Creating a not null constraint Creating a not null constraint at table creation time: SQL > CREATE TABLE EMP(EMPNO NUMBER,ENAME VARCHAR2(20) NOT NULL,…..); Creating a not null constraint after the table has been created: SQL > ALTER TABLE EMP MODIFY (SAL NUMBER

CONSTRAINT MY_EMP_CON NOT NULL;



Creating a foreign key constraint Creating a foreign key constraint at table creation time: SQL > CREATE TABLE EMP(EMPNO NUMBER,ENAME, VARCHAR2(20),..DEPTNO NUMBER CONSTRAINT FKEY_DEPT REFERENCES

DEPT(DEOTNO));



Creating a foreign key constraint

Creating a foreign key constraint after the table has been created:

SQL > ALTER TABLE EMP

ADD CONSTRAINT FKEY_DEPT

FOREIGN KEY (DEPTNO)

REFERENCES DEPT(DEPTNO);



Data Dictionary Constraint Views

The following data dictionary views are used to keep track of constraints that have been defined:

• DBA_CONSTRAINTS – Constraint definitions (OWNER, TYPE ETC…)

• DBA_CONS_COLUMNS – Name of the column in the constraint definition


APPLICATION DEVELOPMENTEstimating Table Size

Table Field Sizes:

• Date fields = 7 bytes• Character fields = 1 byte per character• Number of bytes for numerical fields = precession/2 + 1

Create Table TEST(EMPNO NUMBER(4)ENAME VARCHAR2(15),HIRE_DATE DATE,SAL NUMBER(7,2));

Record Size = (4/2+1) + 15 + 7 + (7/2+1) = 28.5 bytes

APPLICATION DEVELOPMENTEstimating Tablespace Extent Sizes

Place like sized tables in their own tablespace:

• Small tables and indexes - 128 MB and smaller– Tablespace INITIIAL and NEXT Extent Size = 128KB

• Medium sized tables and indexes - 128MB to 4GB– Tablespace INITIIAL and NEXT Extent Size = 4MB

• Large tables and indexes - 4 GB and higher– Tablespace INITIIAL and NEXT Extent Size = 4MB

This is done to reduce tablespace fragmentation


REPLICATION

Replication – Used to copy of one or more tables from one database to another.

• Simple Replication - One way replication using the SNAPSHOT feature

• Oracle Advanced Replication - Uses the Oracle supplied package DBMS_REPCAT to implement two way or master to master replication

• Uses the SNP background process on the primary machine to replicate the data to the secondary server

• Used to populate a report server or data warehouse

REPLICATION cont.

Simple Replication – Replication (secondary) site database setup to replicate the “emp” table:

• Create the snapshot (replicate the table):

SQL > create snapshot emp SQL > refresh fast SQL > start with sysdate SQL > next (sysdate+1) + 03/24 /* refresh every 24 hours.

at 3:00 AM */SQL > as select * from scott.emp@master_site_alias;

REFRESH = FAST – For Incremental table updatesREFRESH = COMPLETE – For a complete table update.


Summary:

• Use ER modeling to determine the applications base tables and the relationships between them

• Use database constraints to implement business rules

• Determine the amount of data that must be stored

• Size data and index tablespace extents according to the size of the objects that will be stored in them


INTRODUCTION TO ORACLE Lynnwood Brown System Managers LLC Application Development For DBA’s...

Documents

Transcript of INTRODUCTION TO ORACLE Lynnwood Brown System Managers LLC Application Development For DBA’s...