Question

Select distinct ename,sal from emp where deptno=30 order by deptno 哪些正确呢？

Select distinct ename,sal from emp where deptno=30 order by deptno

Select * from emp where deptno=30 order by ename

Select 'Name: '|| ename ,sal from emp Where deptno=30 Order by 2,1

Select ename "Employee",sal "salary" from emp Order by "salary" desc , "Employee"，deptno

哪些正确呢？哪位大师帮忙解答下.谢了。

Answer 1

前三条是正确的，最后一条order by 后面字段不能有引号

追问

能帮忙解释下怎么判断哪个对哪个错？

追答

基本语法按标准SQL及具体数据库SQL，然后拿到数据库SQL客户端运行一下就知道是否正确了。