查询问题：求平均单价。

在分组汇总查询中，选择表达式，可以设置公式，在求得分组汇总的前提下，计算平均单价。

如下列查询代码所示

SELECT tblGxdmx.kdid, tblKd.kdmc, tblGxdmx.spid, tblCodeSp.spmc, Sum(tblGxdmx.sl2) AS sl2Sum, Sum(tblGxdmx.je2) AS je2Sum, IIf([sl2sum]=0,0,Round([je2sum]/[sl2sum],4)) AS dj2Avg
FROM ((tblGxdmx INNER JOIN tblKd ON tblGxdmx.kdid=tblKd.kdid) INNER JOIN tblCodeSp ON tblGxdmx.spid=tblCodeSp.spid) INNER JOIN tblGxd ON tblGxdmx.ywdid=tblGxd.ywdid
WHERE (((tblGxd.ywrq)<Date()))
GROUP BY tblGxdmx.kdid, tblKd.kdmc, tblGxdmx.spid, tblCodeSp.spmc
HAVING (((tblGxdmx.kdid)="KB100001") AND ((tblGxdmx.spid)="SP0001"));