DELETE Statement

You can remove existing rows from a table by using the DELETE statement :

• DELETE [FROM] table [WHERE condition];

Deleting Rows from a Table :
Specific rows are deleted if you specify the WHERE clause :

• DELETE FROM dept WHERE dname = 'Finance';

All rows in the table are deleted if you omit the WHERE clause :

• DELETE FROM copy_emp;

Deleting Rows Based on Another Table :

• Use subqueries in DELETE statements to remove rows from a table based on values from another table :
• DELETE FROM emp WHERE deptno = (SELECT deptno FROM dept WHERE dname =‘SALES’);

UPDATE Statement Syntax

Modify existing rows with the UPDATE statement :

• UPDATE table SET column = value [, column = value, ...] [WHERE condition];
• Update more than one row at a time (if required).

Updating Rows in a Table :

Specific row or rows are modified if you specify the WHERE clause :

• UPDATE emp SET deptno = 40 WHERE empno = 7654;

All rows in the table are modified if you omit the WHERE clause :

• UPDATE copy_emp SET deptno = 110;

Updating Two Columns with a Subquery :

• Update employee 7654’s job and sal to match that of employee 7698

UPDATE emp SET job = (SELECT job FROM emp WHERE empno = 7698), sal = (SELECT sal FROM emp WHERE empno = 7698) WHERE empno = 7654;