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SQL中left join(左关联)right join(右关联)join(内关联)的区别

云卷云舒xj 2022-01-31 阅读 102

咋们来实战一下

一、先查出表两个表的数据

SELECT * FROM apps t1

SELECT * FROM user t2;

 

二、left join(左关联)

SELECT * FROM apps t1
LEFT JOIN `user` t2
ON t1.id=t2.id

 三、right join(右关联)

SELECT * FROM apps t1
RIGHT JOIN `user` t2
ON t1.id=t2.id

 四、join(内关联)

SELECT * FROM apps t1
JOIN `user` t2
ON t1.id=t2.id

 

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