b1(ddh,bm,je)
b2(ddh,bm,je,sj)
b1中有6条数据,b2中没有数据以下为我的sql语句,为什么结果集为什么是0了?当b2中没有数据,想要结果集要怎么改了?
select m.b1_cnt-n.b2_cnt,m.b1_j-n.b2_j from
(select b1.bm,count(b1.ddh) b1_cnt,sum(je) b1_j from b1 group by bm) m
left join
(select b2.bm, count(b2.ddh) b2_cnt sum(je) b2_j from b2 where ddh in (select ddh from b1)) n
on m.bm=n.bm
select m.b1_cnt-isnull(n.b2_cnt,0),m.b1_j-isnull(n.b2_j,0.00) from
(select b1.bm,count(b1.ddh) b1_cnt,sum(je) b1_j from b1 group by bm) m
left join
(select b2.bm, count(b2.ddh) b2_cnt sum(je) b2_j from b2 where ddh in (select ddh from b1)) n
on m.bm=n.bm