Access里面有个表1和表2，怎么样在查询里面做到下面的查询结果？

bbg

Access里面有个表1和表2，怎么样在查询里面做到下面的查询结果？表1的mc和sl1是一对多关系，表2的mc和sl2是一对一关系。谢谢！请看下图：

bbg

多谢多谢,代码里面的aa,a,bb,b分别代表什么意思?

bbg

经测试,当数据量大时,每个表有7.8000条,处理比较慢,有时没有响应,查询可以优化吗?另外,如果,表1的字段是mc1,sl1,表2的字段是mc2,sl2时,这个语句该怎么写啊?谢谢!

cg1

别名，用于区分各个表，因为一个表可能套嵌多次

loadhigh

bbg：你好!

查询代码如下：

select aa.mc,aa.sl1,bb.sl2,bb.sl2-aa.sl1 as 差 from (SELECT a.mc, Sum(a.sl1) AS sl1 FROM 表1 AS a GROUP BY a.mc) aa, (SELECT a.mc, Sum(a.sl2) AS sl2 FROM 表2 AS a GROUP BY a.mc) bb where aa.mc = bb.mc union select b.mc,0,sum(b.sl2) as sl2,sum(b.sl2) from 表2 b where mc not in(select mc from 表1) group by mc union select a.mc,sum(a.sl1) as sl1,0,-sum(a.sl1) from 表1 a where mc not in(select mc from 表2) group by mc