SQL查詢合並多個結果

Question

我試圖運行一個SQL查詢以在1行而不是不同的行上顯示日期，我還需要確定每個顯示的日期之間的天數。

請在當前查詢下面找到。

SELECT "Pat_Name",
    CASE WHEN "vw_Schedule"."Activity" = '123'
THEN "vw_Schedule"."App_DtTm"
ELSE NULL
END as Consult,
    CASE WHEN "vw_Schedule"."Activity" = '456'
THEN "vw_Schedule"."App_DtTm"
ELSE NULL
END as SIM,
    CASE WHEN "vw_Schedule"."Activity" = '789'
THEN "vw_Schedule"."App_DtTm"
ELSE NULL
END as PLANNING,
CASE WHEN "vw_Schedule"."SysDefStatus" = 'SC'
          THEN "vw_Schedule"."App_DtTm"
         ELSE NULL
END as TreatmentStart,
          CASE WHEN "vw_Schedule"."SysDefStatus" = 'FC'
          THEN "vw_Schedule"."App_DtTm"
       ELSE NULL   
   END as TreatmentFinished
FROM "vw_Schedule"
WHERE  "vw_Schedule"."Activity"='123' 
or "vw_Schedule"."Activity"='456'
or "vw_Schedule"."Activity"='789'
or "vw_Schedule"."SysDefStatus"='SC'
or "vw_Schedule"."SysDefStatus"='FC'

我希望輸出與下面類似

Pat_Name | Consult  | Days |    SIM   | Days |  PLANNING | Days | TreatmentStart | Days |  TreatmentFinish

Test Pat | 1/9/2013 |   4  | 5/9/2013 |  10  | 15/9/2013 |  3   |    18/9/2013   |   7  |  25/9/2013

謝謝你的幫助。

Answer 1

如果可以保證每個pat_Name的每個活動只有一行，則可以安全地使用聚合函數為每個pat_name的每個活動獲取App_dtTm，而不必擔心丟失數據。 如果沒有重復項，則使用MIN還是MAX也無關緊要。

SELECT  s.Pat_Name,
        Consult = MAX(CASE WHEN s.Activity = '123' THEN s.App_DtTm END),
        SIM = MAX(CASE WHEN s.Activity = '456' THEN s.App_DtTm END),
        PLANNING = MAX(CASE WHEN s.Activity = '789' THEN s.App_DtTm END),
        TreatmentStart = MAX(CASE WHEN s.SysDefStatus = 'SC' THEN s.App_DtTm END),
        TreatmentFinished = MAX(CASE WHEN s.SysDefStatus = 'FC' THEN s.App_DtTm END)
FROM    vw_Schedule s
WHERE   s.Activity IN ('123', '456', '789')
OR      s.SysDefStatus IN ('SC', 'FC')
GROUP BY s.Pat_Name;

如果您一次活動可能有重復的日期，那么您使用的是MIN還是MAX都會有所不同。

為了獲得活動之間的間隔時間，您可以將上面的查詢移到一個通用的表表達式（或者您願意的話可以是子查詢），並簡單地引用您創建的列：

WITH T AS
(   SELECT  s.Pat_Name,
            Consult = MAX(CASE WHEN s.Activity = '123' THEN s.App_DtTm END),
            SIM = MAX(CASE WHEN s.Activity = '456' THEN s.App_DtTm END),
            PLANNING = MAX(CASE WHEN s.Activity = '789' THEN s.App_DtTm END),
            TreatmentStart = MAX(CASE WHEN s.SysDefStatus = 'SC' THEN s.App_DtTm END),
            TreatmentFinished = MAX(CASE WHEN s.SysDefStatus = 'FC' THEN s.App_DtTm END)
    FROM    vw_Schedule s
    WHERE   s.Activity IN ('123', '456', '789')
    OR      s.SysDefStatus IN ('SC', 'FC')
    GROUP BY s.Pat_Name
)
SELECT  Pat_Name,
        Consult,
        Days = DATEDIFF(DAY, Consult, SIM),
        SIM,
        Days = DATEDIFF(DAY, SIM, PLANNING),
        PLANNING,
        Days = DATEDIFF(DAY, PLANNING, TreatmentStart),
        TreatmentStart,
        Days = DATEDIFF(DAY, TreatmentStart, TreatmentFinish),
        TreatmentFinish
FROM    T;