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  • 2017-3-13 SQL server 表连接

    表连接分为横向表连接和纵向表连接

    横向表连接有三种方式:

    1、select 列名,列名 from 表名,表名 where 表名.列名=表名.列名

    select student.Sno,sname,cno,degree from Student,Score
    where Student.Sno = Score.Sno

    2、子查询方式

    select sno,sname,(select cno from Score where Student.Sno=Score.Sno) from Student

    3、select 列名,列名 from 表名 join 表名 on 表名.列名=表名.列名

    select Student.Sno,sname,Score.Cno,DEGREE,cname
    from Student join Score on Student.Sno=Score.Sno
    join Course on Score.Cno = Course.cno

     纵向表连接:(注:两个表必须是同样的列数,对应的列数据类型必须一致)

    select  列名,列名 from 表名 union select  列名,列名 from 表名

    select sno 编号,sname 姓名,ssex 性别,sbirthday 生日 from Student
    union
    select tno,tname,tsex,tbirthday from Teacher

    --------------------------------------------------------------------------------------------------------------------------------------------

    灵活用法

    select Student.sno,sname+'同学',cname,abs(degree+10)
    from Student,Score,Course
    where Student.Sno=Score.Sno and Score.Cno=Course.Cno
    and student.Sno='107'

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  • 原文地址:https://www.cnblogs.com/zhengqian/p/6544341.html
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