sql union 语句 case语句
摘要:
1:Union语句: 把两个结果合为一体(但是完全重复的数据会去掉) Eg1: select name, age, ‘学生无工资’ from student union select name, age, sal from teacher Eg2: select top 2 CONVERT(varc 阅读全文
posted @ 2017-05-17 11:59 改变从今天开始 阅读(565) 评论(0) 推荐(0) 编辑