我有两个表t_tran_log和t_item_master。
当我针对t_tran_log运行此查询时，我得到了准确的结果：
declare @startdate as datetime; declare @enddate as datetime
set @startdate = '9/13/20 5am'; set @enddate = dateadd(hour,24,@startdate)
select
cast(t.start_tran_date+t.start_tran_time - '1900-01-01 05:00' as date) tran_date
,t.item_number
,sum(t.tran_qty) qty
from t_tran_log t
where t.start_tran_date+t.start_tran_time >= @startdate
and t.start_tran_date+t.start_tran_time < @enddate
and t.tran_type = '750' and t.description like 'Customer Return' and t.hu_id not like '1Z%'
group by cast(t.start_tran_date+t.start_tran_time - '1900-01-01 05:00' as date), t.item_number
但是，当我尝试通过左联接从另一个表中提取其他物料详细信息时，我突然得到的物料数量结果翻倍！我在做什么错了？
declare @startdate as datetime; declare @enddate as datetime
set @startdate = '9/13/20 5am'; set @enddate = dateadd(hour,24,@startdate)
select
cast(t.start_tran_date+t.start_tran_time - '1900-01-01 05:00' as date) Date
,t.item_number
,i.dept_name
,i.class_name
,i.subclass_name
,sum(t.tran_qty) qty
from t_tran_log t
left join t_item_master i on t.item_number = i.item_number
where t.start_tran_date+t.start_tran_time >= @startdate
and t.start_tran_date+t.start_tran_time < @enddate
and t.tran_type = '750' and t.description like 'Customer Return' and t.hu_id not like '1Z%'
group by cast(t.start_tran_date+t.start_tran_time - '1900-01-01 05:00' as date), t.item_number, i.dept_name, i.class_name, i.subclass_name
答案 0 :(得分：0)
很可能，.buttons-wrapper{
display: inline-block;
border: 1px solid grey;
padding: 10px 5px;
border-radius: 5px;
}
.buttons-wrapper .btn{
width: 200px;
height: 30px;
color: blue;
font-weight: 600;
}
中有多个行符合联接条件。结果，行相乘，聚合函数出错。
首先考虑在子查询中进行预聚合：
item_master