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MySQL數據庫中如何解決分組統計的問題

來源:互聯網  2008-06-01 02:20:09  評論

首先准備四張表A、B、C、D,

--------------------------------

A |B |C |D

a b | a c | a d | d e

1 1 | 1 1 | 1 A | A 1

2 2 | 1 3 | 2 B | B 2

3 4 | 1 4 | 3 C | C 3

4 6 | 2 1 | 4 D | D 4

--------------------------------

下面我們需要用一條sql語句將A表所有的列,B表對與A表a字段相關聯的列求count,通過C表,將D表與A表關聯起來,得到的結果如下:

1 1 3 1

2 2 1 2

3 4 0 3

4 6 0 4

Mysql語句解決:

select A.a,A.b,IFNULL(c,0) as c,D.a

from (select 1 as a,2 as b union all

select 2 as a,2 as b union all

select 3 as a,4 as b union all

select 4 as a,6 as b) as A

left outer join

(select a,count(a) as c from(

select 1 as a,3 as c union all

select 1 as a,3 as c union all

select 1 as a,3 as c union all

select 2 as a,3 as c ) B group by a) as B

on A.a=B.a

join

(select 1 as a,'A' as d union all

select 2 as a,'B' as d union all

select 3 as a,'C' as d union all

select 4 as a,'D' as d ) as C

on A.a=C.a

join(select 1 as a,'A' as d union all

select 2 as a,'B' as d union all

select 3 as a,'C' as d union all

select 4 as a,'D' as d ) as D

on D.d=C.d

首先准備四張表A、B、C、D, -------------------------------- A  | B  | C  | D a b | a c | a d | d e 1 1 | 1 1 | 1 A | A 1 2 2 | 1 3 | 2 B | B 2 3 4 | 1 4 | 3 C | C 3 4 6 | 2 1 | 4 D | D 4 -------------------------------- 下面我們需要用一條sql語句將A表所有的列,B表對與A表a字段相關聯的列求count,通過C表,將D表與A表關聯起來,得到的結果如下: 1 1 3 1 2 2 1 2 3 4 0 3 4 6 0 4 Mysql語句解決: select A.a,A.b,IFNULL(c,0) as c,D.a from (select 1 as a,2 as b union all select 2 as a,2 as b union all select 3 as a,4 as b union all select 4 as a,6 as b) as A left outer join (select a,count(a) as c from( select 1 as a,3 as c union all select 1 as a,3 as c union all select 1 as a,3 as c union all select 2 as a,3 as c ) B group by a) as B on A.a=B.a join (select 1 as a,'A' as d union all select 2 as a,'B' as d union all select 3 as a,'C' as d union all select 4 as a,'D' as d ) as C on A.a=C.a join(select 1 as a,'A' as d union all select 2 as a,'B' as d union all select 3 as a,'C' as d union all select 4 as a,'D' as d ) as D on D.d=C.d
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