同時選擇字段的最短日期和最大日期

Question

我有這個查詢，它返回字段的最小日期值。

SELECT sa.ContentID, SA.MSISDN, sa.DateRegistered AS minDate, sa.DateRegistered AS maxDate 
FROM sms.dbo.SubscriptionsArchive AS sa 
INNER JOIN (SELECT MSISDN, MIN(DateRegistered) AS mindate 
      FROM sms.dbo.SubscriptionsArchive 
      GROUP BY MSISDN) mysa 
ON sa.MSISDN = mysa.MSISDN AND sa.DateRegistered = mysa.mindate 

它的輸出是

但我想除了顯示在同一日期的最大日期值以及到最小日期。我如何實現這一目標？

Answer 1

雖然它可能是很有誘惑力使用第二子查詢聯接，以獲得MAX()，並再次MSISDN的最大日加入，你應該能夠通過添加MAX(DateRegistered)到現有的子查詢並添加OR來實現它條件在聯接的ON子句中加入MSISDN,mindate或MSISDN,maxdate。

SELECT 
    sa.ContentID, 
    SA.MSISDN, 
    -- Use the join's dates by alias in the SELECT 
    mysa.mindate, 
    mysa.maxdate 
FROM 
    sms.dbo.SubscriptionsArchive AS sa 
    INNER JOIN (
    SELECT 
     MSISDN, 
     MIN(DateRegistered) AS mindate, 
     -- Add the max date 
     MAX(DateRegistered) AS maxdate, 
    FROM sms.dbo.SubscriptionsArchive 
    GROUP BY MSISDN 
) mysa 
    -- Join on either a mindate or maxdate match 
    ON (sa.MSISDN = mysa.MSISDN AND sa.DateRegistered = mysa.mindate) 
     OR (sa.MSISDN = mysa.MSISDN AND sa.DateRegistered = mysa.maxdate) 

我注意到你這個標記爲mysql但dbo真的建議你使用的是MS SQL服務器。如果這是真的，那麼你可以使用公用表表達式而不是子查詢連接。

-- Define the subquery as a CTE instead 
WITH mysa AS (
SELECT 
    MSISDN, 
    MIN(DateRegistered) AS mindate, 
    -- Add the max date 
    MAX(DateRegistered) AS maxdate, 
    FROM sms.dbo.SubscriptionsArchive 
    GROUP BY MSISDN 
); 

SELECT 
    sa.ContentID, 
    SA.MSISDN, 
    -- Use the join's dates by alias in the SELECT 
    mysa.mindate, 
    mysa.maxdate 
FROM sms.dbo.SubscriptionsArchive AS sa 
-- Join on the CTE 
INNER JOIN mysa 
    ON (sa.MSISDN = mysa.MSISDN AND sa.DateRegistered = mysa.mindate) 
    OR (sa.MSISDN = mysa.MSISDN AND sa.DateRegistered = mysa.maxdate) 

Answer 2

您的語法建議SQL Server。如果是的話，我會建議窗口功能：

SELECT sa.ContentID, SA.MSISDN, sa.DateRegistered AS minDate, sa.DateRegistered AS maxDate 
FROM (SELECT sa.*, 
      MIN(DateRegistered) OVER (PARITION BY sa.MSISDN) as mindr, 
      MAX(DateRegistered) OVER (PARITION BY sa.MSISDN) as maxdr 
     FROM sms.dbo.SubscriptionsArchive sa 
    ) sa 
WHERE sa.DateRegistered IN (mindr, maxdr);