#MYSQL子查询

子查询 由[NOT] IN引发的子查询

SELECT id FROM department;

SELECT id,username FROM employee WHERE depid IN(1,2,3,4);

上2句 下1句；

SELECT id,username FROM employee WHERE depid IN(SELECT id FROM department);

EXISTS (判断是否为真,真才执行外面的语句)

ANY 或者 SOME或者ALL子查询

=最小值 ANY SOME 最大值ALL

<=最大值 ANY SOME 最小值ALL

=任意值 ANY SOME

<> != 任意值 ALL

例如:SELECT id,username FROM shtuden WHERE score>=ANY(SELECT level FROM scholar)

将查询结果写入到数据列表

INSERT test(id,num)

SELECT id,score FROM studen;