Question

这是我到目前为止为我的查询编写的代码：

     select
         workorderkey,
         WarrantyRoutingStep, 
         StepOrder
     from tblFAWOWarrantyRoutingsOEM WarrantyRoutings
     where 
workorderkey=220870 and --fyi i do not want to do this
StepCompleteDate IS NULL

结果就是这个

Current Output

如何让它看起来像这样，所以它只返回StepOrder列中具有最小值的行）？请注意，我不仅仅想要workorderkey 220870的结果;我希望它能够为每个workorderkey分组并返回一个结果 - 只需输入该过滤器进行测试。

Desired Output

请原谅图片而不是桌面结果的文字。第一次海报，长达一个月的观众。几周前刚刚开始编写SQL。

Answer 1

如果您的dbms支持窗口函数，那么很容易：

SELECT *
FROM
    (
       select
          workorderkey,
          WarrantyRoutingStep, 
          StepOrder,
          ROW_NUMBER() OVER (PARTITION BY workorderkey ORDER BY StepOrder) as RowNumber
       from tblFAWOWarrantyRoutingsOEM WarrantyRoutings
       where StepCompleteDate IS NULL
    ) t
WHERE
    t.RowNumber = 1

没有窗口功能，你仍然可以：

SELECT wr2.*
FROM
    (
       select
          workorderkey,
          MIN(StepOrder) as MinStepOrder
       from tblFAWOWarrantyRoutingsOEM WarrantyRoutings
       where StepCompleteDate IS NULL
       GROUP BY
          workorderkey
    ) t
    INNER JOIN tblFAWOWarrantyRoutingsOEM wr2
    On t.workorderkey = wr2.workorderkey
    AND StepCompleteDate IS NULL

但如果步骤顺序不是每个工单的唯一，那么后一种方法仍然可以结束。

Answer 2

select 
     min(StepOrder),
     workorderkey,
     WarrantyRoutingStep
 from tblFAWOWarrantyRoutingsOEM WarrantyRoutings
 where StepCompleteDate IS NULL
 GROUP BY workorderkey, WarrantyRoutingStep

这适用于你

SQL从多个键

2 个答案: