在SQL Server的VIEW中使用DECLARE

Question

我需要做這樣的事情：

CREATE VIEW MyView AS 
DECLARE @MAXDATE AS Date 
@MAXDATE = SELECT MAX(insertdate) FROM Mytable
SELECT * FROM Mytable WHERE insertdate= MAXDATE

每天都有新行插入到我的表中，我需要獲取最后一次插入的子集。 但是我不能這樣做，因為視圖不允許使用DECLARE。

有人嗎

謝謝！

Answer 1

SELECT * FROM Mytable WHERE insertdate = (SELECT MAX(insertdate) FROM Mytable)

Answer 2

您也可以這樣做：

CREATE VIEW MyView AS 
    SELECT TOP (1) WITH TIES t.*
    FROM Mytable t
    ORDER BY CAST(insertdate as date) DESC;

如果已經將insertdate聲明為日期，則不需要cast() ：

CREATE VIEW MyView AS 
    SELECT TOP (1) WITH TIES t.*
    FROM Mytable t
    ORDER BY insertdate DESC;

為了提高性能，我建議在mytable(insertdate)上建立索引。