MYSQL OR与AND一起 的用法

MYSQL OR与AND一起 的用法

在MySQL中 or 的用法

-- 查询结果是id = 2且age = 20或者id=1
SELECT * from student WHERE id = 1 or id = 2 AND age = 20;

-- 查询结果是 id=1或id=2 且age = 20
SELECT * from student WHERE (id = 1 or id = 2 ) AND age = 20;

犯错记录：要求查出 INVOICE_TITLE like ‘12%’或者CLIENT_NAME LIKE ‘%12%’的数据，结果前台一直报请求超时，发现数据多了将近20倍，SQL如下

SELECT * FROM ewin_should_receive sr, ewin_client_snap cs WHERE sr.client_snap_id = cs.id AND sr.b_enable = '1' AND cs.INVOICE_TITLE LIKE '%12%' OR cs.CLIENT_NAME LIKE '%12%'

//正确SQL

SELECT * FROM ewin_should_receive sr, ewin_client_snap cs WHERE sr.client_snap_id = cs.id AND sr.b_enable = '1' AND ( cs.INVOICE_TITLE LIKE '%12%' OR cs.CLIENT_NAME LIKE '%12%' )