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SQL多表联系查询

本文主要是介绍SQL多表联系查询,对大家解决编程问题具有一定的参考价值,需要的程序猿们随着小编来一起学习吧!

SQL多表联系查询

首先二张表连接查询:A表:EUser  B表:ESchool

一、外连接:左连接、右连接、全然外连接。

左连接:left join 或 left outer join

  select * from EUser left join ESchool  on EUser.SchoolId=ESchool.ScholId 

右连接:right join 或 right outer join

select * from EUser right join ESchool  on EUser.SchoolId=ESchool.ScholId 

全然外连接:  full join 或 full outer join

  select * from EUser full join ESchool  on EUser.SchoolId=ESchool.ScholId 

二、内连接: join 或 inner join

select * from EUser INNER JOIN ESchool  on EUser.SchoolId=ESchool.ScholId 

三张表连接查询:A表:EUser  B表:ESchool  C表:EXibu

方法一:

  select * from EUser INNER JOIN ESchool  on EUser.SchoolId=ESchool.ScholId 
  INNER JOIN EXibu on ESchool.ScholId=EXibu.SchoolId and EUser.DepartmentId=EXibu.DepartmentId

方法二:

  select * from EUser as sc left join ESchool as s on s.ScholId=sc.SchoolId
  left join EXibu as c on c.DepartmentId=sc.DepartmentId

了解内连接与外连接可以:https://www.cnblogs.com/mvpbest/p/13879121.html

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