在MSSQL Server中通过查看SQL语句执行所用的时间，来衡量SQL语句的性能。
通过设置STATISTICS我们可以查看执行SQL时的系统情况。选项有PROFILE，IO ，TIME。介绍如下：
SET STATISTICS PROFILE ON：显示分析、编译和执行查询所需的时间（以毫秒为单位）。
SET STATISTICS IO ON：报告与语句内引用的每个表的扫描数、逻辑读取数（在高速缓存中访问的页数）和物理读取数（访问磁盘的次数）有关的信息。
SET STATISTICS TIME ON：显示每个查询执行后的结果集，代表查询执行的配置文件。
语句示例：
SET STATISTICS PROFILE ON;
SET STATISTICS IO ON;
SET STATISTICS TIME ON;
GO
/*--你的SQL脚本开始*/
SELECT [GroupBy1].[A1] AS [C1]
FROM ( SELECT COUNT(1) AS [A1]
FROM [dbo].[Questions] AS [Extent1]
WHERE ( [Extent1].[CheckUser] IS NOT NULL )
AND ( NOT ( ( N'' = [Extent1].[CheckUser] )
AND ( [Extent1].[CheckUser] IS NOT NULL )
)
)
AND ( [Extent1].[Source] IN ( N'xxx1', N'xxx2', N'xxx3' ) )
AND ( [Extent1].[Source] IS NOT NULL )
) AS [GroupBy1];
/*你的SQL脚本结束*/
GO
SET STATISTICS PROFILE OFF;
SET STATISTICS IO OFF;
SET STATISTICS TIME OFF;