各位,請幫個忙~~ 下面兩條語句請問有什麼差異呢?請問可以寫出與“語句一”等價的表達式嗎?謝謝。
語句一:
SELECT DISTINCT CNAME
FROM COURSES C WHERE '男'=all (select sex from enrolls,students where enrolls.sno=students.sno and enrolls.cno=C.cno)語句二:
select distinct cname from courses,students,enrolls where students.sno=enrolls.sno and courses.cno=enrolls.cno and students.sex='男'
語句一:
SELECT DISTINCT CNAME
FROM COURSES C WHERE '男'=all (select sex from enrolls,students where enrolls.sno=students.sno and enrolls.cno=C.cno)語句二:
select distinct cname from courses,students,enrolls where students.sno=enrolls.sno and courses.cno=enrolls.cno and students.sex='男'
解决方案 »
- 不同种类统计请教
- SQLServer 输出XML 查询语句
- SQL一些存储过程被删除了怎么恢复?
- 关于查询的问题~~~~~~~~~~~~~~~~~~~
- dwr怎么和sql数据库绑定
- 两个表中的列相互参照的问题
- 各位哥哥,帮我看看吧(急急急,在线等)
- 救命啊~~~~~~~~~~~SQL SERVER打死也装不上
- bulk insert 速度问题
- 简单问题请教:用SQl语句删除一个表中的字段该怎样写?
- SQL-Server2000安装出问题,装了.NET 2005后,怎么也装不上SQL-Serverle!!!
- ALTER DATABASE pubs SET RECOVERY SIMPLE 有什么用?
SELECT DISTINCT CNAME
FROM COURSES C WHERE '男' in (select sex from enrolls,students where enrolls.sno=students.sno and enrolls.cno=C.cno)