1、distinct

select count(distinct CName) from teble
select count(CName) from (select distinct CName from Course) as temp
SELECT  DISTINCT text_zhcn FROM dms_menuconfig  -- 去重查询表中数据
select DISTINCT(user_id) from user_info where children_merchant_id='kuaiditong';

 

2、group by

select count(1) from Course group by CName

 

文档:mysql去重查询表中数据.note
链接:http://note.youdao.com/noteshare?id=581440d92396bab4de6568d1a69baa58&sub=9B8DAB091CC5490BA5F8FA29557CCD67

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