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===============================问题描述===================================
两个表
表users
id username
1 andy
2 jack
3 leo
4 kimi
表car
id title userid chnname
1 bmw750 1 宝马
2 bmw530 1 宝马
3 bmw 2 宝马
4 benzc2 1 奔驰
5 benzE3 2 奔驰
SQL：select * from a.*,b.* from car a inner join username b on a.userid = b.id
现在需要增加like查询条件 查询title类似于bmw的
select * from a.*,b.* from car a inner join username b on a.userid = b.id and a.title like '%bmw%'
这个语句会得到三条结果。正确的。但如果我再加上一个like条件就不行
查询title类似于bmw chnname类似于宝马
select * from a.*,b.* from car a inner join username b on a.userid = b.id and a.title like '%bmw%' or a.chnname like '%宝马%'
这样的话会得到一大堆的重复数据
==============================分析=================================
之所以会得到那么多重复数据是因为上面的SQL相当于
select a.*,b.* 
from car a 
inner join username b 
on a.userid = b.id AND a.title like '%bmw%'
UNION ALL
select a.*,b.* 
from car a 
inner join username b 
on a.chnname like '%宝马%'
===============================解决=================================
在like条件中加()或者使用where
1.select * from a.*,b.* from car a inner join username b on a.userid = b.id and 
(a.title like '%bmw%' or a.chnname like '%宝马%')
2.select a.*,b.* from car a inner join username b on a.userid = b.id 
where a.title like '%bmw%' or a.chnname like '%宝马%'