同时选择字段的最小日期和最大日期

Question

我有这个查询，它返回相应字段的最小日期值。

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它的输出是

但我想显示同一日期的最大日期值以及最小日期。我如何实现这一目标？

Answer 1

尽管使用第二个子查询联接来获取MAX()并再次通过MSISDN加入最新日期可能很诱人，但您应该可以通过添加{{MAX(DateRegistered)来实现它。 1}}进入现有子查询并在联接的OR子句中添加ON条件，以加入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)

我注意到您将此标记为mysql，但dbo确实建议您使用的是MS SQL Server。如果是这样，那么您可以使用公用表表达式而不是子查询连接。

-- 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

您的语法建议使用SQL Server。如果是这样，我建议使用窗口函数：

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);