Question

我很确定这是一件容易的事，但我是SQL的新手，所以要温柔。如果我想编写一个查询，它会将每个进程号的总出现次数加起来并将这些值存储到新列中，我该怎么办？我认为计数的一些混合（不同......）可以让它失效但我不确定。请参阅结果表了解我正在寻找的内容。

Order_Table:

order_number     process 
         100           8
         100           7
         100           7
         100           6
         100           5
         105           6
         105           2
         105           4

Results:

order_num    NumOfEight   NumOfSeven   NumOfSix   NumOfFive  NumOfFour  NumOfTwo
      100             1            2          1           1          0         0
      105             0            0          1           0          1         1

更新：我使用SQL 2005作为基础，但可以访问更新的版本。过程是一组有限的值。

Answer 1

假设SQL Server 2005+，您可以使用PIVOT

SELECT 
      order_num, [8] AS NumOfEight, [7] AS NumOfSeven   /* etc. etc.*/
FROM 
      (SELECT order_number AS order_num, process FROM Order_Table) p
PIVOT 
      (COUNT(process) FOR process IN ([8],[7] /* etc. etc.*/)) pvt

Answer 2

select order_num,
       sum(case when process = 8 then 1 else 0 end) as NumOfEight,
       sum(case when process = 7 then 1 else 0 end) as NumOfSeven,
       sum(case when process = 6 then 1 else 0 end) as NumOfSix
       /* Repeat as many times as needed */
    from Order_Table
    group by order_num

选择一组不同的值并将它们分别计数到新列中

2 个答案: