求sql如何连接2个不同关键字求和结果
如表#T 列名为 A B a_b b_a
A，B分别是两个参数的ID， a_b表示由A求得B的值，b_a表示由B求得A的值
现在想将 select sum(a_b) from #T group by A 和 select sum（b_a） from #T group by B 两个表连接显示成 A B sum（a_b） sum（b_a) 怎么写join语句？ 谢谢了
[最优解释]
select * from(select A,sum(a_b) as sum_a from dbo.test group by A) as t1
left join
(select * from (select B,sum(b_a) as sum_b from dbo.test group by B) as t2) as t3
on t1.A=t3.B;
[其他解释]
select A,sum(a_b) from #T group by A
union
select B,sum（b_a） from #T group by B
[其他解释]
SELECT MAX(A) A ,
MAX(B) B ,
SUM(suma_b) suma_b ,
SUM(sumb_a) sumb_a
FROM ( SELECT A ,
NULL B ,
SUM(a_b) suma_b ,
0 sumb_a
FROM #T
GROUP BY A
UNION
SELECT NULL A ,
B ,
0 suma_b ,
SUM(b_a) sumb_a
FROM #T
GROUP BY B
) A
