提取从动态SQL返回的值

Question

我有一个存储过程,它生成并执行一段动态T-SQL,一旦建立起来就像这样

SELECT 
    tblUsers.strUserName AS [Username]
    ,tblUsers.strEmail AS [Email]
    ,tblUserAuditLog.strIpAddress AS [IP Address]
    ,tblUserAuditLog.dtAuditTimeStamp AS [Timestamp]
    ,tblUserAuditLog.strAuditLogAction AS [Action]
    ,tblUserAuditLog.strLogDetails AS [Details]
FROM         
    tblUserAuditLog 
        LEFT OUTER JOIN tblUsers 
        ON tblUserAuditLog.intUserIdFK = tblUsers.intUserId
WHERE 
    tblUsers.strUserName = 'a12jun'
    AND tblUserAuditLog.dtAuditTimeStamp >= '2012-08-10'

此查询可以在开发环境中返回几千行,并将在实时返回更多.

我想知道在实际返回结果之前动态查询返回了多少行,这样如果数量超过某个限制,我可以返回"缩小查询"错误消息.

我试过像这样生成另一块SQL:

DECLARE @sqlrowcount NVARCHAR(MAX);
SET @sqlrowcount = 'SELECT COUNT(*) FROM (' + @sql + ') AS TEMP';
EXEC(@sqlrowcount);

IF @@ROWCOUNT > @limit BEGIN .... END

@sql动态查询在哪里.然后我尴尬地意识到EXEC(@sqlrowcount)将永远返回1,因为它返回一个记录,其值是记录的数量.

有没有(相对)优雅的方式,例如没有将结果写入临时表？

Answer 1

单程;

--base sql
declare @sql  nvarchar(255) = N'select * from master.dbo.spt_values'

--count wrapper
declare @sqlb nvarchar(255) = N'set @count=(select count(*) from (' + @sql + ') T)'

declare @count int
exec sp_executesql @sqlb, N'@count int output', @count output

select 'rows=',@count

您还可以使用TOP强制执行限制,两次运行相同的语句效率不高.