模糊查询

select * from emp where ename like '%A%'

select * from emp where ename like 'A%' --ename只要首字母是A的就输出

select * from emp where ename like '%A' --ename只要尾字母是A的输出

select * from emp where ename like '_A%' --ename只要第二个字母是A的就输出

select * from emp where ename like '_[A-F]%' --a-f的任意字符

select * from emp where ename like '_[^A-F]%' --把enam中第二个字符不是a至f的单个字符

select * from emp where ename like '_[A,F]%' --把enam中第二个字符不是af的输出

select * from student where name like '%%%' escape ''