临时表删除法
查看数据
mysql> select * from emp1 ;
+-------+--------+-----------+------+---------------------+------+------+--------+
| empNO | ENAME | JOB | MGR | HIREDATE | SAL | COMM | deptNO |
+-------+--------+-----------+------+---------------------+------+------+--------+
| 7369 | SMITH | CLERK | 7902 | 1980-12-17 00:00:00 | 800 | NULL | 20 |
| 7499 | ALLEN | SALESMAN | 7698 | 1981-02-20 00:00:00 | 1600 | 300 | 30 |
| 7521 | WARD | SALESMAN | 7698 | 1981-02-22 00:00:00 | 1250 | 500 | 30 |
| 7566 | JONES | MANAGER | 7839 | 1981-04-02 00:00:00 | 2975 | NULL | 20 |
| 7654 | MARTIN | SALESMAN | 7698 | 1981-09-28 00:00:00 | 1250 | 1400 | 30 |
| 7698 | BLAKE | MANAGER | 7839 | 1981-05-01 00:00:00 | 2850 | NULL | 30 |
| 7782 | CLARK | MANAGER | 7839 | 1981-06-09 00:00:00 | 2450 | NULL | 10 |
| 7788 | SCOTT | ANALYST | 7566 | 1987-04-19 00:00:00 | 3000 | NULL | 20 |
| 7839 | KING | PRESIDENT | NULL | 1981-11-17 00:00:00 | 5000 | NULL | 10 |
| 7844 | TURNER | SALESMAN | 7698 | 1981-09-08 00:00:00 | 1500 | 0 | 30 |
| 7876 | ADAMS | CLERK | 7788 | 1987-05-23 00:00:00 | 1100 | NULL | 20 |
| 7900 | JAMES | CLERK | 7698 | 1981-12-03 00:00:00 | 950 | NULL | 30 |
| 7902 | FORD | ANALYST | 7566 | 1981-12-03 00:00:00 | 3000 | NULL | 20 |
| 7934 | MILLER | CLERK | 7782 | 1982-01-23 00:00:00 | 1300 | NULL | 10 |
+-------+--------+-----------+------+---------------------+------+------+--------+
14 rows in set (0.00 sec)
执行删除语句
mysql> delete from emp1
-> where empno in
-> (select empno from
-> ( select empno
-> from emp1 e1
-> where e1.sal > (select avg(sal) from emp1 e2 where e1.deptno=e2.deptno ) ) temtable) ;
Query OK, 6 rows affected (0.01 sec)
查看结果
mysql> select * from emp1 ;
+-------+--------+----------+------+---------------------+------+------+--------+
| empNO | ENAME | JOB | MGR | HIREDATE | SAL | COMM | deptNO |
+-------+--------+----------+------+---------------------+------+------+--------+
| 7369 | SMITH | CLERK | 7902 | 1980-12-17 00:00:00 | 800 | NULL | 20 |
| 7521 | WARD | SALESMAN | 7698 | 1981-02-22 00:00:00 | 1250 | 500 | 30 |
| 7654 | MARTIN | SALESMAN | 7698 | 1981-09-28 00:00:00 | 1250 | 1400 | 30 |
| 7782 | CLARK | MANAGER | 7839 | 1981-06-09 00:00:00 | 2450 | NULL | 10 |
| 7844 | TURNER | SALESMAN | 7698 | 1981-09-08 00:00:00 | 1500 | 0 | 30 |
| 7876 | ADAMS | CLERK | 7788 | 1987-05-23 00:00:00 | 1100 | NULL | 20 |
| 7900 | JAMES | CLERK | 7698 | 1981-12-03 00:00:00 | 950 | NULL | 30 |
| 7934 | MILLER | CLERK | 7782 | 1982-01-23 00:00:00 | 1300 | NULL | 10 |
+-------+--------+----------+------+---------------------+------+------+--------+
8 rows in set (0.00 sec)
关联删除法
查看数据
mysql> select * from emp1 ;
+-------+--------+-----------+------+---------------------+------+------+--------+
| empNO | ENAME | JOB | MGR | HIREDATE | SAL | COMM | deptNO |
+-------+--------+-----------+------+---------------------+------+------+--------+
| 7369 | SMITH | CLERK | 7902 | 1980-12-17 00:00:00 | 800 | NULL | 20 |
| 7499 | ALLEN | SALESMAN | 7698 | 1981-02-20 00:00:00 | 1600 | 300 | 30 |
| 7521 | WARD | SALESMAN | 7698 | 1981-02-22 00:00:00 | 1250 | 500 | 30 |
| 7566 | JONES | MANAGER | 7839 | 1981-04-02 00:00:00 | 2975 | NULL | 20 |
| 7654 | MARTIN | SALESMAN | 7698 | 1981-09-28 00:00:00 | 1250 | 1400 | 30 |
| 7698 | BLAKE | MANAGER | 7839 | 1981-05-01 00:00:00 | 2850 | NULL | 30 |
| 7782 | CLARK | MANAGER | 7839 | 1981-06-09 00:00:00 | 2450 | NULL | 10 |
| 7788 | SCOTT | ANALYST | 7566 | 1987-04-19 00:00:00 | 3000 | NULL | 20 |
| 7839 | KING | PRESIDENT | NULL | 1981-11-17 00:00:00 | 5000 | NULL | 10 |
| 7844 | TURNER | SALESMAN | 7698 | 1981-09-08 00:00:00 | 1500 | 0 | 30 |
| 7876 | ADAMS | CLERK | 7788 | 1987-05-23 00:00:00 | 1100 | NULL | 20 |
| 7900 | JAMES | CLERK | 7698 | 1981-12-03 00:00:00 | 950 | NULL | 30 |
| 7902 | FORD | ANALYST | 7566 | 1981-12-03 00:00:00 | 3000 | NULL | 20 |
| 7934 | MILLER | CLERK | 7782 | 1982-01-23 00:00:00 | 1300 | NULL | 10 |
+-------+--------+-----------+------+---------------------+------+------+--------+
14 rows in set (0.00 sec)
执行语句
mysql> delete emp1 from emp1 ,(select deptno,avg(sal) a_sal from emp1 group by deptno) emp2
-> where emp1.deptno=emp2.deptno
-> and emp1.sal > emp2.a_sal ;
Query OK, 6 rows affected (0.09 sec)
查看结果
mysql> select * from emp1 ;
+-------+--------+----------+------+---------------------+------+------+--------+
| empNO | ENAME | JOB | MGR | HIREDATE | SAL | COMM | deptNO |
+-------+--------+----------+------+---------------------+------+------+--------+
| 7369 | SMITH | CLERK | 7902 | 1980-12-17 00:00:00 | 800 | NULL | 20 |
| 7521 | WARD | SALESMAN | 7698 | 1981-02-22 00:00:00 | 1250 | 500 | 30 |
| 7654 | MARTIN | SALESMAN | 7698 | 1981-09-28 00:00:00 | 1250 | 1400 | 30 |
| 7782 | CLARK | MANAGER | 7839 | 1981-06-09 00:00:00 | 2450 | NULL | 10 |
| 7844 | TURNER | SALESMAN | 7698 | 1981-09-08 00:00:00 | 1500 | 0 | 30 |
| 7876 | ADAMS | CLERK | 7788 | 1987-05-23 00:00:00 | 1100 | NULL | 20 |
| 7900 | JAMES | CLERK | 7698 | 1981-12-03 00:00:00 | 950 | NULL | 30 |
| 7934 | MILLER | CLERK | 7782 | 1982-01-23 00:00:00 | 1300 | NULL | 10 |
+-------+--------+----------+------+---------------------+------+------+--------+
8 rows in set (0.00 sec)