SQL Server 2012 多表连接查询功能实例代码

INNER JOIN dbo.ClassInfo ON dbo.Student.Class = dbo.ClassInfo.ID;
on 条件，通常是 主外键，但是不限于主外键
on 条件，允许有多个，而且可能是针对某个表的
SELECT *
FROM Student
INNER JOIN dbo.ClassInfo ON dbo.Student.Class = dbo.ClassInfo.ID
AND dbo.Student.Class IN (1,2) 针对Student表增加查询条件
不等于 (笛卡尔值减去 相等的值)
SELECT *
FROM Student
INNER JOIN dbo.ClassInfo ON dbo.Student.Class dbo.ClassInfo.ID;
自连接 从Class表中查询到Class所在的系
SELECT T1.* ,T2.ClassName FROM dbo.ClassInfo AS T1
INNER JOIN dbo.ClassInfo AS T2 ON T1.PID=T2.ID
Left Join
SELECT *
FROM Student
Left JOIN dbo.ClassInfo ON dbo.Student.Class = dbo.ClassInfo.ID;
Right Join
SELECT *
FROM Student
RIGHT JOIN dbo.ClassInfo ON dbo.Student.Class = dbo.ClassInfo.ID;
全外连接
SELECT *
FROM Student
FULL OUTER JOIN dbo.ClassInfo ON dbo.Student.Class = dbo.ClassInfo.ID;
外连接和内连接的区别是：
内连接，on条件不符合的话，会过滤掉数据
外连接，以保留表为主，on条件成立显示数据，否则显示NULL
Union 纵向连接
SELECT StuID,StuName,StuEnName,StuAge,StuBirthday
FROM Student WHERE StuID =2
UNION
SELECT StuID,StuName,StuEnName,StuAge,StuBirthday
FROM dbo.Student WHERE StuID 2
Union 去重复
SELECT StuSex
FROM Student WHERE StuID =2
UNION
SELECT StuSex
FROM dbo.Student WHERE StuID 2
Union 显示全部
SELECT StuSex
FROM Student WHERE StuID =2
UNION ALL
SELECT StuSex
FROM dbo.Student WHERE StuID 2
Except 差集,排除
SELECT StuID,StuName,StuEnName,StuAge,StuBirthday
FROM Student
Except
SELECT StuID,StuName,StuEnName,StuAge,StuBirthday
FROM dbo.Student WHERE StuID =2
Intersect 交集
SELECT StuID,StuName,StuEnName,StuAge,StuBirthday
FROM Student WHERE StuID =2
Except
SELECT StuID,StuName,StuEnName,StuAge,StuBirthday
FROM dbo.Student WHERE StuID =3

以上所述是小编给大家介绍的SQL Server 2012 多表连接查询功能实例代码，希望对大家有所帮助，如果大家有任何疑问欢迎给我留言，小编会及时回复大家的！

我想要获取技术服务或软件
服务范围：MySQL、ORACLE、SQLSERVER、MongoDB、PostgreSQL 、程序问题
服务方式：远程服务、电话支持、现场服务，沟通指定方式服务
技术标签：数据恢复、安装配置、数据迁移、集群容灾、异常处理、其它问题

本站部分文章参考或来源于网络，如有侵权请联系站长。
数据库远程运维 SQL Server 2012 多表连接查询功能实例代码