日期时间的转换

Question

我有以下疑问：

set @DataEnd = '
          select top 1 datetime 
          from IntradayHistory.dbo.IntradayDataHistory' + @product + ' 
          where TickerID = ' + cast(@ticker as nvarchar(24)) + ' 
          order by datetime desc
'
exec(@DateEnd)

这应该只返回 1 个值，它确实返回了：

但是，由于我需要该值作为 DateTime 进行动态查询，我应该怎么做？

Answer 1

使用sp_executesql，您可以将输出参数发送到动态查询。

DECLARE @sqlCommand NVARCHAR(MAX);
DECLARE @dateEnd DATETIME;
SET @sqlCommand = '
          select top 1 @retVal = datetime 
          from IntradayHistory.dbo.IntradayDataHistory' + @product + ' 
          where TickerID = ' + cast(@ticker as nvarchar(24)) + ' 
          order by datetime desc
';
EXECUTE sp_executesql @sqlCommand, N'@retVal DATETIME OUTPUT', @retVal=@dateEnd OUTPUT;
SELECT @dateEnd;

选项 B：

您可以使用临时表来存储动态查询的结果。

DECLARE @sqlCommand NVARCHAR(MAX);
SET @sqlCommand = '
      select top 1 datetime 
      from IntradayHistory.dbo.IntradayDataHistory' + @product + ' 
      where TickerID = ' + cast(@ticker as nvarchar(24)) + ' 
      order by datetime desc
';
CREATE TABLE #temp1 (Result DATETIME);
INSERT INTO #temp1 EXEC (@sqlCommand);
SELECT * FROM #temp1;