MySQL的更新
select * from emp;
select * from dept1;
查询语句
update emp a,dept b set a.sal=a.sal*b.deptno,b.deptname=a.ename where a.deptno=b.deptno;
删除记录
delete from emp where ename='dony';
查询部分字段
select ename,hiredate,sal,deptno from emp;
查询不重复的字段
select distinct deptno from emp;
条件查询
select * from emp where deptno=1;
select * from emp where deptno=1 and sal<3000;