exec失败，因为名称不是有效的标识符？

问题描述：

我有一个查询我需要运行它作为动态查询输出一个有意义的列名称。作为一个例子，如果我直接运行查询，它会正确返回数据。但是，如果我用下面的代码，它显示：exec失败，因为名称不是有效的标识符？

The name ' 
      SELECT (CASE WHEN A.Domain IS NOT NULL THEN A.Domain ELSE B.Domain END) AS [Domain], 
        (CASE WHEN A.Email IS NOT NULL THEN A.Email ELSE B.Email END) AS [Email], 
        A.[Sender Size] AS [Sender Size 1], A.[Sender Count] AS [Sender Count 1], 
         A.[Receiver Size] AS [Receiver Size 1], A.[Receiver Count] AS [Receiver Count 1], 
        A.[Sender Size 2] AS [Sender Size 2], A.[Sender Count 2] AS [Sender Count 2], 
         A.[Receiver Size 2] AS [Receiver Size 2], A.[Receiver Count 2] AS [Receiver Count 2], 
        B.SenderSize AS [Sender Size Average], B.SenderCount AS [Sender Count Average], 
         B.ReceiverSize AS [Receiv' is not a valid identifier.

在它下面是代码：

DECLARE @query NVARCHAR(4000) 
SET @query = N'SELECT * 
      FROM 
      (
       SELECT (CASE WHEN A.Domain IS NOT NULL THEN A.Domain ELSE B.Domain END) AS [Domain], 
         (CASE WHEN A.Email IS NOT NULL THEN A.Email ELSE B.Email END) AS [Email], 
         A.[Sender Size] AS [Sender Size 1], A.[Sender Count] AS [Sender Count 1], 
          A.[Receiver Size] AS [Receiver Size 1], A.[Receiver Count] AS [Receiver Count 1], 
         A.[Sender Size 2] AS [Sender Size 2], A.[Sender Count 2] AS [Sender Count 2], 
          A.[Receiver Size 2] AS [Receiver Size 2], A.[Receiver Count 2] AS [Receiver Count 2], 
         B.SenderSize AS [Sender Size Average], B.SenderCount AS [Sender Count Average], 
          B.ReceiverSize AS [Receiver Size Average], B.ReceiverCount AS [Receiver Count Average] 
       FROM 
        (
        SELECT (CASE WHEN tf.Domain IS NOT NULL THEN tf.Domain ELSE tf2.Domain END) AS Domain, 
          (CASE WHEN tf.Email IS NOT NULL THEN tf.Email ELSE tf2.Email END) AS Email, 
         ISNULL(tf.SenderSize,0) AS [Sender Size] , ISNULL(tf.SenderCount,0) AS [Sender Count], ISNULL(tf.ReceiverSize,0) AS [Receiver Size], ISNULL(tf.ReceiverCount,0) AS [Receiver Count], 
         ISNULL(tf2.SenderSize,0) AS [Sender Size 2], ISNULL(tf2.SenderCount,0) AS [Sender Count 2], ISNULL(tf2.ReceiverSize,0) AS [Receiver Size 2], ISNULL(tf2.ReceiverCount,0) AS [Receiver Count 2] 
        FROM #TrafficFinal tf FULL JOIN #TrafficFinal2 tf2 ON (tf.Email = tf2.Email AND tf.Domain = tf2.Domain) 
        ) A FULL JOIN #TrafficFinal3 B ON (A.Email = B.Email AND A.Domain = B.Domain) 
      ) C 
      ORDER BY Domain, Email';  

PRINT @query; 

-- run it 
exec @query;

是因为充分加入？

对不起。我花了一段时间才弄清楚可以点击检查符号。 – urlreader 2012-08-16 17:20:19

答

尝试这一句结尾：

exec (@query)

如果没有括号，SQL Server假定该变量的值是一个存储过程的名称。

EXECUTE sp_executesql @query

，它不应该是因为FULL JOIN的。
但我希望你已经创建了临时表：#TrafficFinal，＃TrafficFinal2，＃TrafficFinal3在此之前。

请注意，使用EXEC和sp_executesql之间有性能方面的考虑因素。因为sp_executesql像sp一样使用强制语句缓存。
更多详细信息here。

在另一方面，是有一个原因，你正在使用动态SQL这种情况下，你可以直接使用的查询，考虑你是不是做任何的查询操作，并执行它，它是这样的？

非常感谢，我知道我错过了一些简单的事情！ :) – urlreader 2012-08-16 17:10:39

这是因为列标题，即接收方计数1，...需要用户友好的日期变量。 – urlreader 2012-08-16 17:22:03

我刚碰到同样的问题，感谢解决方案。我觉得很愚蠢，不是因为它太简单。 – Jackson 2013-05-08 16:56:43

答

正如在我的情况下，如果通过连接产生的SQL或用途转换，然后在执行需要SQL来与字母N前缀如下

例如

Exec N'Select bla..'

N定义字符串文字是unicode。

exec失败，因为名称不是有效的标识符？

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