Join with union returns 我错了结果

Question

我需要使用 union all 两次。然后用相同的table加入他们。第一个 union 将包含一个 where 语句，而第二个则不包含。问题是，当我使用第二个 table 时，我的结果发生了变化。

select sum(x.quantity*x.Price)
from CustomerTrans t1 
inner join (
    select *
    from InventoryTrans
    union all
    select *
    from InventoryTransTemp
) x on t1.TrnDocumentID = x.TrnDocumentID
group by t1.TrnDocumentID

这是此结果的输出

First Result

然后我添加第二个联合，其中包含 where 语句

select sum(x.quantity*x.Price), sum(x2.quantity*x2.Price)
from CustomerTrans t1 
left join (
    select *
    from InventoryTrans
    union all
    select *
    from InventoryTransTemp
) x on t1.TrnDocumentID = x.TrnDocumentID
left join (
    select *
    from InventoryTrans
    where printed = 2 or InvoicePaymentID = 2 
    union all
    select *
    from InventoryTransTemp
    where printed = 2 or InvoicePaymentID = 2
) x2 on t1.TrnDocumentID = x2.TrnDocumentID 
group by t1.TrnDocumentID

这是第二个结果

Second Result

第二个结果应该是 3.80 而不是 7.60

看起来它是我的价格 *2 而不是 *1 的倍数。

Answer 1

这里发生的是您加入了您不想加入的行。假设您的第一个子查询 returns

+----------+-------+
| quantity | price |
+----------+-------+
|       10 |   100 |
|       10 |   200 |
+----------+-------+

针对特定文档 ID。而你的第二个子查询 returns only

+----------+-------+
| quantity | price |
+----------+-------+
|       10 |   200 |
+----------+-------+

合并结果为：

+------------+---------+-------------+----------+
| x.quantity | x.price | x2.quantity | x2.price |
+------------+---------+-------------+----------+
|         10 |     100 |          10 |      200 |
|         10 |     200 |          10 |      200 |
+------------+---------+-------------+----------+

之后的聚合结果为：

+----------+-----------+
| x_result | x2_result |
+----------+-----------+
|     3000 |      4000 |
+----------+-----------+

而不是

+----------+-----------+
| x_result | x2_result |
+----------+-----------+
|     3000 |      2000 |
+----------+-----------+

您不想连接单行，而是连接聚合结果（每个文档的总数）：

select 
  ct.*,
  coalesce(u1.total, 0) as u1_total,
  coalesce(u2.total, 0) as u2_total
from customertrans ct
left join 
(
  select trndocumentid, sum(quantity * price) as total
  from
  (
    select * from inventorytrans
    union all
    select * from inventorytranstemp
  ) union1
  group by trndocumentid
) u1 on u1.trndocumentid = ct.trndocumentid
left join 
(
  select trndocumentid, sum(quantity * price) as total
  from
  (
    select * from inventorytrans where printed = 2 or invoicepaymentid = 2 
    union all
    select * from inventorytranstemp where printed = 2 or invoicepaymentid = 2
  ) union2
  group by trndocumentid
) u2 on u2.trndocumentid = ct.trndocumentid 
group by ct.trndocumentid
order by ct.trndocumentid;

Join with union returns 我错了结果

Join with union returns me wrong result

sql

sql-server

tsql

sql-server-2019