MySQL使用左联接时发生错误

Question

当我在mysql中使用左联接时，有两条数据，但我确信只有一条数据会出来

sql是

SELECT bs.id,distribute_user_id,manager_id,phone,manager_name 
FROM   bank_integral_distribute_serial bs 
         LEFT JOIN manager mi ON bs.distribute_user_id = mi.manager_id 
WHERE bs.phone = "13978836385"

​

​

各自的数据sql是

SELECT  * 
FROM    bank_integral_distribute_serial 
WHERE   distribute_user_id="1475118915817316353"

​

​

sql是

SELECT  * 
FROM    manager 
WHERE   manager_id = "1475118915817316353"

​

​

我还查了一下手机号码，只有一个

在这里输入图像描述

问题:为什么有两条数据？

Answer 1

原因是MySQL比较类型不一致。

你可以看到

https://dev.mysql.com/doc/refman/5.7/en/type-conversion.html

distribute_user_id原来的表是bigint : manager_id是varchar

SELECT IF("1475118915817316353"=1475118915817316354,"equal","unequal") //The results are equal

SELECT IF("1475118915817316311"=1475118915817316360,"enqual","unequal") //The results are equal

//left：[1475118915817316224，1475118915817316480] The results are equal, both with the right side
SELECT IF("1475118915817316480"=1475118915817316360,"enqual","unenqual")