Question

SQL语句如何将两个表格的数据合并查询出来，然后求某个字段对应另外一个数据字段的和，急急急

两个表格通过FItemID连接查询（查询的结果为每个Fitem都有好几个期初数据），然后求Fitem对应期初数据的和，
select t6.FItemID as 物料代码,
t5.FPeriod as 期初取数期间,
sum(t5.FBegQty) as 期初数据
from ICInvBal t5 inner join t_ICItem t6 on t6.FItemID=t5.FItemID
where t5.FPeriod=9
and t5.FItemID=260
order by t5.FItemID
运行时出现错误：
消息 8120，级别 16，状态 1，第 2 行
选择列表中的列 't_ICItem.FItemID' 无效，因为该列没有包含在聚合函数或 GROUP BY 子句中

Answer 1

用sum的话必须要加group by，所有非聚合函数都要出现在group by 列
select t6.FItemID as 物料代码,
t5.FPeriod as 期初取数期间,
sum(t5.FBegQty) as 期初数据
from ICInvBal t5 inner join t_ICItem t6 on t6.FItemID=t5.FItemID
where t5.FPeriod=9
and t5.FItemID=260
GROUP BY t6.FItemID, t5.FPeriod
order by t5.FItemID

Answer 2

select t6.FItemID as 物料代码,
t5.FPeriod as 期初取数期间,
sum(t5.FBegQty) as 期初数据
from ICInvBal t5 inner join t_ICItem t6 on t6.FItemID=t5.FItemID
where t5.FPeriod=9
and t5.FItemID=260 group by t6.FItemID,t5.FPeriod
order by t5.FItemID