SELECT c.ID,IF(c.A=0,NULL,c.A) A,IF(c.B=0,NULL,c.B) B,IF(c.C=0,NULL,c.C) C FROM
(SELECT a.ID,
(SELECT COUNT(*) FROM t WHERE aid=ID) A,
(SELECT COUNT(*) FROM t WHERE bid=ID) B,
(SELECT COUNT(*) FROM t WHERE cid=ID) C
FROM
(SELECT aid ID FROM t
UNION
SELECT bid FROM t
UNION
SELECT cid FROM t) a WHERE NOT ID IS NULL) c

------解决方案--------------------
SQL code

select v,
    sum(if(k='A',1,0)) as A,
    sum(if(k='B',1,0)) as B,
    sum(if(k='C',1,0)) as C
from (
    select 'A' as k, aid as v from 一个表
    union all
    select 'B' as k, bid as v from 一个表
    union all
    select 'C' as k, cid as v from 一个表
) t
group by v

------解决方案--------------------

得到上面的T表后可以有多种方法实现行列转换。

MySQL交叉表
http://blog.csdn.net/acmain_chm/article/details/4283943