如何 select 为每个唯一 ID 单独一行

Question

SQL 新手在此求职学习，还是个新手。 我有一个问题，我不知道如何克服。 使用 IBM Netezza 和 Aginity Workbench。

我当前的 output 将尝试根据创建任务的时间为每个案例编号返回一行。 它只会保留最新任务的行。 这使我完成了大约 85% 的工作。 问题是有时多个任务的创建日是同一天。

如果有多行具有相同的案例编号，我想合并任务跟进日期以仅保留最新的行。 我将我当前代码输出的示例以及我想要的示例发布到 output。

当前代码

SELECT 
     A.PS_CASE_ID AS Case_Number
     ,D.CASE_TASK_TYPE_NM AS Task
     ,C.TASK_CRTE_TMS
     ,C.TASK_FLWUP_DT AS Task_Followup_Date


FROM VW_CC_CASE A
     INNER JOIN VW_CASE_TASK C ON (A.CASE_ID = C.CASE_ID)
     INNER JOIN VW_CASE_TASK_TYPE D ON (C.CASE_TASK_TYPE_ID = D.CASE_TASK_TYPE_ID)
     INNER JOIN ADMIN.VW_RSN_CTGY B ON (A.RSN_CTGY_ID = B.RSN_CTGY_ID)


WHERE 
     (A.PS_Z_SPSR_ID LIKE '%EFT' OR A.PS_Z_SPSR_ID LIKE '%CRDT')
     AND CAST(A.CASE_CRTE_TMS AS DATE) >= '2020-01-01'
     AND B.RSN_CTGY_NM = 'Chargeback Initiation'
     AND CAST(C.TASK_CRTE_TMS AS DATE) = (SELECT MAX(CAST(C2.TASK_CRTE_TMS AS DATE)) from VW_CASE_TASK C2 WHERE C2.CASE_ID = C.CASE_ID)


GROUP BY 
     A.PS_CASE_ID
     ,D.CASE_TASK_TYPE_NM
     ,C.TASK_CRTE_TMS
     ,C.TASK_FLWUP_DT

当前 output

所需 output

Answer 1

您可以在此处使用ROW_NUMBER ：

WITH cte AS (
    SELECT DISTINCT A.PS_CASE_ID AS Case_Number, D.CASE_TASK_TYPE_NM AS Task,
        C.TASK_CRTE_TMS, C.TASK_FLWUP_DT AS Task_Followup_Date,
        ROW_NUMBER() OVER (PARTITION BY A.PS_CASE_ID ORDER BY C.TASK_FLWUP_DT DESC) rn
    FROM VW_CC_CASE A
    INNER JOIN VW_CASE_TASK C ON A.CASE_ID = C.CASE_ID
    INNER JOIN VW_CASE_TASK_TYPE D ON C.CASE_TASK_TYPE_ID = D.CASE_TASK_TYPE_ID
    INNER JOIN ADMIN.VW_RSN_CTGY B ON A.RSN_CTGY_ID = B.RSN_CTGY_ID
    WHERE (A.PS_Z_SPSR_ID LIKE '%EFT' OR A.PS_Z_SPSR_ID LIKE '%CRDT') AND
          CAST(A.CASE_CRTE_TMS AS DATE) >= '2020-01-01' AND
          B.RSN_CTGY_NM = 'Chargeback Initiation' AND
          CAST(C.TASK_CRTE_TMS AS DATE) = (SELECT MAX(CAST(C2.TASK_CRTE_TMS AS DATE))
                                           FROM VW_CASE_TASK C2
                                           WHERE C2.CASE_ID = C.CASE_ID)
)

SELECT
    Case_Number,
    Task,
    TASK_CRTE_TMS,
    Task_Followup_Date
FROM cte
WHERE rn = 1;

Answer 2

一种方法使用 window 函数：

with cte as (
      < your query here >
     )
select x.*
from (select cte.*,
             row_number() over (partition by case_number, Task_Followup_Date
                                order by TASK_CRTE_TMS asc
                               ) as seqnum
      from cte
     ) x
where seqnum = 1;