MYSQL学习心得(6) -- SQL子查询的一些例子

1、单行子查询

select ename,deptno,sal

from emp

where deptno=(select deptno from dept where loc='NEW YORK')；

2、多行子查询

SELECT ename,job,sal

FROM EMP

WHERE deptno in ( SELECT deptno FROM dept WHERE dname LIKE 'A%')；

3、多列子查询

SELECT deptno,ename,job,sal

FROM EMP

WHERE (deptno,sal) IN (SELECT deptno,MAX(sal) FROM EMP GROUP BY deptno)；

4、内联视图子查询

(1)SELECT ename,job,sal,rownum

FROM (SELECT ename,job,sal FROM EMP ORDER BY sal)；

(2)SELECT ename,job,sal,rownum

FROM ( SELECT ename,job,sal FROM EMP ORDER BY sal)

WHERE rownum<=5；

5、在HAVING子句中使用子查询

SELECT deptno,job,AVG(sal) FROM EMP GROUP BY deptno,job HAVING AVG(sal)>(SELECT sal FROM EMP WHERE ename='MARTIN')；