THE RELATIONAL DATA BASE (RDB) AND STRUCTURED QUERY LANGUAGE (SQL)

• Based on relational theory

• Relational model first introduced by Dr. E.F Codd in early 70s

• First prototype system developed by IBM in the mid 70s

• First commercial version from ORACLE in 1979

History:

THE RELATIONAL DATA BASE (RDB) AND STRUCTURED QUERY LANGUAGE (SQL)

• RDBs are now the standard for data storage

• SQL is the standard for accessing and manipulating RDBs

• SQL is an ANSI standard in the public domain

• SQL is implemented by many vendors including all major

data base systems

Current status:

Description of an RDB:

• Data stored in related tables

• Tables made up of rows and columns

• Rows in are uniquely identified by a primary key

• Rows in different tables are related by a foreign key

• Non-procedural

• Works on an entire set of data at a time

• Has English like syntax

• Very concise and powerful

• Combines functionality of the data step and

several procedures into a single statement

Description of SQL:

DNAME LOC DEPTNO

ACCOUNTING NEW YORK 10

RESEARCH DALLAS 20

SALES CHICAGO 30

OPERATIONS BOSTON 40

EMPNO ENAME JOB MGR HIREDATE SAL DEPTNO COMM

7369 SMITH CLERK 7902 17DEC80 $800 20 .

7499 ALLEN SALESMAN 7698 20FEB81 $1,600 30 $300

7521 WARD SALESMAN 7698 22FEB81 $1,250 30 $500

7566 JONES MANAGER 7839 02APR81 $2,975 20 .

7654 MARTIN SALESMAN 7698 28SEP81 $1,250 30 $1,400

7698 BLAKE MANAGER 7839 01MAY81 $2,850 30 .

7782 CLARK MANAGER 7839 09JUN81 $2,450 10 .

7788 SCOTT ANALYST 7566 19APR87 $3,000 20 .

7839 KING PRESIDENT . 17NOV81 $5,000 10 .

7844 TURNER SALESMAN 7698 08SEP81 $1,500 30 $0

7876 ADAMS CLERK 7788 23MAY87 $1,100 20 .

7900 JAMES CLERK 7698 03DEC81 $950 30 .

7902 FORD ANALYST 7566 03DEC81 $3,000 20 .

7934 MILLER CLERK 7782 23JAN82 $1,300 10 .

EMP Table (Detail table)

DEPT Table (Mater table)

1

*

A ONE-TO-MANY RELATIONSHIP

PK

PK

FK

SELECT variable list FROM table list;

STRUCTURE OF SQL SELECT STATEMENT SYNTAX

SELECT variable list FROM table list WHERE condition;

SELECT variable list FROM table list WHERE conditionORDER BY variable list;

SELECT variable list FROM table list WHERE condition

GROUP BY variable list HAVING condition

ORDER BY variable list;