为什么我无法设置值

Question

这个陈述有什么问题，当我没有设置@label

时它会起作用

Declare
     @SourceTable varchar(255) = '[ServerXX\XX].[database].[dbo].[Manager]',
     @Label varchar(255)

     SET @Label = (SELECT Manager 
                FROM (
                    SELECT Manager, ROW_NUMBER() OVER (ORDER BY ManagerID) AS RowNum
                    FROM @SourceTable
                     ) AS MyDerivedTable 
                WHERE MyDerivedTable.RowNum = 2);

                print @Label

错误：但是当我用[ServerXX \ XX]更改@SourceTable时。[数据库]。[dbo]。[经理] ......它有效但我想使用我的@SourceTable

Must declare the table variable "@SourceTable".