問題描述

只會差尋一列，求教如何查詢多列數據重復個數！

問題解答

我的意見是數據庫簡單提取數據后，有業務端處理，寫各種復雜的select查詢影響效率

select distinct q1,t1.count1,tt.q2,tt.count2 ... from tleft join (select q1,count(1) count1 from t group by q1) t1 on t1.q1 = t.q1full join ( select distinct q2,t2.count2 from t left join (select q2,count(1) count1 from t group by q2) t2 on t2.q1 = t.q1) tt on tt.q2 = t.q1 ...

感覺好粗鄙，等大神來。

select a.*,b.q2,b.q2Count,c.q3,c.q3Count from (SELECT (@n1:=@n1+1) as id,q1,count(*) AS q1Count FROM t1 GROUP BY q1) a, (SELECT (@n2:=@n2+1) as id,q2,count(*) AS q2Count FROM t1 GROUP BY q2) b, (SELECT (@n3:=@n3+1) as id,q3,count(*) AS q3Count FROM t1 GROUP BY q3) c,(select @n1:=0,@n2:=0,@n3:=0) iwhere a.id=b.id and c.id=a.id

2 D 1 B 2 D 21 B 3 C 2 E 1