mysql去重查询表中数据

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';

select count(1) from Course group by CName