时间:2021-07-01 10:21:17 帮助过:12人阅读
多个like查询会出现大量重复数据 无 ===============================问题描述===================================两个表表usersid username1 andy2 jack3 leo4 kimi表carid title userid chnname1 bmw750 1 宝马2 bmw530 1 宝马3 bmw 2 宝马4 benzc2 1 奔驰
多个like查询会出现大量重复数据 <无>
- ===============================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%'