TSQL 仅显示第一行

Question

我有以下 TSQL 查询:

SELECT DISTINCT MyTable1.Date
  FROM MyTable1 
INNER JOIN MyTable2 
ON MyTable1.Id = MyTable2.Id
WHERE Name = 'John' ORDER BY MyTable1.Date DESC

它检索一长串日期，但我只需要第一个，即第一行中的日期。

我怎样才能得到它？

非常感谢!

Answer 1

在 SQL Server 中，您可以使用 TOP :

SELECT TOP 1 MyTable1.Date
FROM MyTable1 
INNER JOIN MyTable2 
  ON MyTable1.Id = MyTable2.Id
WHERE Name = 'John' 
ORDER BY MyTable1.Date DESC

如果您需要使用DISTINCT，那么您可以使用:

SELECT TOP 1 x.Date
FROM
(
   SELECT DISTINCT MyTable1.Date
   FROM MyTable1 
   INNER JOIN MyTable2 
     ON MyTable1.Id = MyTable2.Id
    WHERE Name = 'John' 
) x
ORDER BY x.Date DESC

或者甚至:

SELECT MAX(MyTable1.Date)
FROM MyTable1 
INNER JOIN MyTable2 
  ON MyTable1.Id = MyTable2.Id
WHERE Name = 'John' 
--ORDER BY MyTable1.Date DESC