count(distinct 订单号）和count(*)as 订单数`````group by 订单号,这两个语句是不是同一个运算结果?

count(distinct 订单号）和count(*)as 订单数`````group by 订单号,这两个语句是不是同一个运算结果? group by 和 distinct 的问题select a.partner as pcode, count(distinct(a.deviceid)) as count -- into num4 from test a where a.activationtime >= to_date('2011-4-17', 'yyyy-mm-dd') and a.activationtime < to_date( distinct select telnum,count(0),count(distinct othertelnum) from nmk.ljdx_cdr_temp group by telnum count,count和count的区别 SQL里的DISTINCT什么意思SELECT Sno,AVG(Grade)FROM SCGROUP BY SnoHAVING COUNT(DISTINCT(Sno))>1;既然已经按Sno分类了,再用DISTINCT那HAVING COUNT(DISTINCT(Sno))的值岂不是只能为1? select count(distinct b) from X_info where c=1;能放到一个CASE内么 不用where group by 等等因为有多个这样的case 所以 where 和groupby 都不能考虑.b是另一张表的主键. distinguish和distinct的区别?如题 distinct 和 distinctive 那一个是“明显的”? select count和select count的区别 count(0)和count(*)哪个效率高? count(0)和count(*)哪个效率高? take for 和 count while（count-j） count count COUNT count