SQL 选择 Top 1 字段并分配给局部变量
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时间：2020-09-01 02:06:32 来源:igfitidea点击:
Select Top 1 field and assign to local variable
提问by Steve Staple
I want to take the value of ExtractedDate from this query and use it as @LastExtractDate in the next query. How do I do that?
我想从此查询中获取 ExtractedDate 的值，并在下一个查询中将其用作 @LastExtractDate 。我怎么做？
SELECT TOP 1 [ExtractedDate]
FROM [OnsiteV4].[dbo].[SqlPendingIndex] order by ExtractedDate desc
next query:
下一个查询：
insert into @table(Hex, KeyDeviceId, ObjectDateTime, ExtractedDate )
SELECT CONVERT(VARCHAR(MAX), CONVERT(VARBINARY(MAX), ObjectValue, 1)) AS Hex, KeyDeviceId, ObjectDateTime , GETDATE ()
FROM SQLPending
WHERE (ObjectSubType LIKE '%GAS%') and (ObjectDateTime > @LastExtractDate)
回答by Brett Schneider
why not use this:
为什么不使用这个：
declare @LastExtractDate date
SELECT TOP 1 @LastExtractDate=[ExtractedDate]
FROM [OnsiteV4].[dbo].[SqlPendingIndex] order by ExtractedDate desc
回答by Alex K.
Simply declare & assign:
只需声明和分配：
DECLARE @LastExtractDate DATETIME = (
SELECT TOP 1 [ExtractedDate] FROM [OnsiteV4].[dbo].[SqlPendingIndex] order by ExtractedDate desc
)
or better:
或更好：
DECLARE @LastExtractDate DATETIME = (
SELECT MAX(ExtractedDate) FROM [OnsiteV4].[dbo].[SqlPendingIndex]
)
回答by Jesuraja
Use this:
用这个：
DECLARE @ExtractedDate DATETIME
SET @ExtractedDate = (SELECT TOP 1 ExtractedDate
FROM [OnsiteV4].[dbo].[SqlPendingIndex]
ORDER BY ExtractedDate DESC
回答by KrushnaKPawar
Try this simply
简单地试试这个
declare @LastExtractDate date
SELECT @LastExtractDate=MAX([ExtractedDate])
FROM [OnsiteV4].[dbo].[SqlPendingIndex]
