Rows can be removed from a table using the DELETE command. For example, the following sequence of commands shows the before and after results of deleting all employees in department 20.
SELECT ename, deptno FROM emp; ename | deptno --------+-------- SMITH | 20 ALLEN | 30 WARD | 30 JONES | 20 MARTIN | 30 BLAKE | 30 CLARK | 10 SCOTT | 20 KING | 10 TURNER | 30 ADAMS | 20 JAMES | 30 FORD | 20 MILLER | 10 (14 rows) DELETE FROM emp WHERE deptno = 20; SELECT ename, deptno FROM emp; ename | deptno --------+-------- ALLEN | 30 WARD | 30 MARTIN | 30 BLAKE | 30 CLARK | 10 KING | 10 TURNER | 30 JAMES | 30 MILLER | 10 (9 rows)
Be extremely careful of giving a DELETE command without a WHERE clause such as the following:
DELETE FROM tablename;
This statement will remove all rows from the given table, leaving it completely empty. The system will not request confirmation before doing this.
