为什么？ UNION ALL 正在做一个计算

Question

我有两个数据集：DS_A和DS_B。

我的问题是为什么 pro_id 71549 有两个数量而不是三个？

ALL 将所有行合并到结果中。这包括重复项。如果未指定，将删除重复的行。

loc_id        pro_id      quantity    price
------------- ----------- ----------- -----------
2310          5052        1           0
2365          5433        1           0
2310          7694        1           0
2310          9480        1           0
2310          9502        1           0
2310          14413       1           0
2310          31277       1           0
2310          46180       1           0
2310          65233       1           0
2310          68369       1           0
2310          68372       1           0
2310          77396       1           0


loc_id        pro_id      quantity    price
------------- ----------- ----------- -----------
2310          71549       0.15         0

当我做我的 UNION ALL:

declare @tax float
set @tax = 0.05

select loc_id
   , pro_id
   , sum(quantity)
   , price
from DS_A
group by loc_id, pro_id
UNION ALL
select 2310
   , 71549
   , case when sum(quantity)<>0 Then sum(quantity/ @tax) Else 0 End
   , price
from DS_B
group by pro_id, loc_id

结果：

loc_id        pro_id      quantity    price
------------- ----------- ----------- -----------
2310          5052        1           0
2365          5433        1           0
2310          7694        1           0
2310          9480        1           0
2310          9502        1           0
2310          14413       1           0
2310          31277       1           0
2310          46180       1           0
2310          65233       1           0
2310          68369       1           0
2310          68372       1           0
2310          77396       1           0
2310          71549       2           0

Answer 1

不确定...适合我，在 Oracle 11 上...您使用的是什么 DBMS，什么版本？

你好像打错了，或者当你认为是 3 时却是 2？如果它之前是3，它肯定应该是UNION之后的3。

  SQL> l
    1  with w_d1 as (
    2           select 2310 as loc_id, 5052  as pro_id, 1 as quantity, 0 as price from dual union all
    3           select 2365 as loc_id, 5433  as pro_id, 1 as quantity, 0 as price from dual union all
    4           select 2310 as loc_id, 7694  as pro_id, 1 as quantity, 0 as price from dual union all
    5           select 2310 as loc_id, 9480  as pro_id, 1 as quantity, 0 as price from dual union all
    6           select 2310 as loc_id, 9502  as pro_id, 1 as quantity, 0 as price from dual union all
    7           select 2310 as loc_id, 14413 as pro_id, 1 as quantity, 0 as price from dual union all
    8           select 2310 as loc_id, 31277 as pro_id, 1 as quantity, 0 as price from dual union all
    9           select 2310 as loc_id, 46180 as pro_id, 1 as quantity, 0 as price from dual union all
   10           select 2310 as loc_id, 65233 as pro_id, 1 as quantity, 0 as price from dual union all
   11           select 2310 as loc_id, 68369 as pro_id, 1 as quantity, 0 as price from dual union all
   12           select 2310 as loc_id, 68372 as pro_id, 1 as quantity, 0 as price from dual union all
   13           select 2310 as loc_id, 77396 as pro_id, 1 as quantity, 0 as price from dual
   14        ),
   15     w_d2 as (
   16           select 2310 as loc_id, 71549 as pro_id, 3 as quantity, 0 as price from dual
   17        )
   18  select loc_id, pro_id, quantity, price from w_d1
   19    union all
   20* select loc_id, pro_id, quantity, price from w_d2
  SQL> /

      LOC_ID     PRO_ID   QUANTITY      PRICE
  ---------- ---------- ---------- ----------
        2310       5052          1          0
        2365       5433          1          0
        2310       7694          1          0
        2310       9480          1          0
        2310       9502          1          0
        2310      14413          1          0
        2310      31277          1          0
        2310      46180          1          0
        2310      65233          1          0
        2310      68369          1          0
        2310      68372          1          0
        2310      77396          1          0
        2310      71549          3          0

  13 rows selected.

Answer 2

当您运行第一个查询和第二个查询或您运行一个服务器上的另一个服务器上的另一个查询之间的数据发生变化。

Answer 3

舍入问题会给您带来麻烦。

旧table结构：

DECLARE Sales_Table     TABLE(
         loc_id          Int,    
         pro_id                 Int,     
         quantity               int, --> on insert caused rounding issues       
         price                  Int )

新table结构：

DECLARE Sales_Table     TABLE(
         loc_id          Int,    
         pro_id                 Int,     
         quantity               decimal(10,2),      
         price                  Int)

我的修复测试：

declare @tax float
set @tax = 0.05

insert into Sales_table --> old table
select loc_id
   , pro_id
   , sum(quantity)
   , price
from DS_A
group by loc_id, pro_id
UNION ALL
select 2310
   , 71549
   , cast(case when sum(0.15)<>0 Then sum(0.15/ @tax) Else 0 End AS float) --> rtns 3
   , price
from DS_B
group by pro_id, loc_id

Answer 4

我怀疑它正在转换为 int 并向下舍入

declare @tax float
set @tax = 0.05
declare @quantityF float
set @quantityF = 0.15 

select @quantityF / @tax                    -- 3
select cast((@quantityF / @tax) as int)     -- 2

您不应该使用浮点数 - 使用小数点

declare @taxD decimal(9,2)
set @taxD = 0.05
declare @quantityD decimal(9,2)
set @quantityD = 0.15 

select @quantityD / @taxD                    -- 3.0000000
select cast((@quantityD / @taxD) as int)     -- 3

为什么？ UNION ALL 正在做一个计算

WHY? UNION ALL is doing a Calculation

sql

tsql

sql-server

sql-server-2005