关于sql语句的疑问

sql2005下，如下sql:

declare @sql varchar(2000)

set @sql='select * from Sysobjects'

exec(@sql)

在此如果不加括号,如（exec @sql），就会提示"找不到存储过程 'select * from Sysobjects'。";

加上括号则可正常执行.

exec执行存储过程或者函数，不用加挎号，否则要加

见 http://msdn.microsoft.com/en-us/library/ms188332.aspx

下面是Exec 的语法

从语法定义可以看出，如果不加挎号， SQL SERVER 就会认为Exec 后面跟的是存储过程或者函数，所以会出现找不到存储过程的错误。

Execute a stored procedure or function


[ { EXEC | EXECUTE } ]


    { 


      [ @return_status = ]


      { module_name [ ;number ] | @module_name_var } 


        [ [ @parameter = ] { value 


                           | @variable [ OUTPUT ] 


                           | [ DEFAULT ] 


                           }


        ]


      [ ,...n ]


      [ WITH RECOMPILE ]


    }


[;]





Execute a character string


{ EXEC | EXECUTE } 


        ( { @string_variable | [ N ]'tsql_string' } [ + ...n ] )


    [ AS { LOGIN | USER } = ' name ' ]


[;]





Execute a pass-through command against a linked server


{ EXEC | EXECUTE }


        ( { @string_variable | [ N ] 'command_string [ ? ] ' } [ + ...n ]


        [ { , { value | @variable [ OUTPUT ] } } [ ...n ] ]


        ) 


    [ AS { LOGIN | USER } = ' name ' ]


    [ AT linked_server_name ]


[;]