Using the result of an [removed]e.g. Function call

问题:

I am trying to write a stored procedure to assist with development of our database, but I am having some trouble using it. For example:

DECLARE @pID int;
SET @pID = 1;
EXEC WriteLog 'Component', 'Source', 'Could not find given id: ' + CAST(@pID AS varchar);

This yields the error (on SQL Server 2005):

Msg 102, Level 15, State 1, Line 4 Incorrect syntax near '+'.

Can someone explain to me why my syntax is incorrect, and the right way to solve this problem?

回答1:

You need to use an intermediate variable. SQL Server does not support this kind of operation in the parameter list itself though it has been on the TODO list for a few years! (See Connect Item: Use scalar functions as stored procedure parameters)

The grammar for EXEC is

[ { EXEC | EXECUTE } ]
    { 
      [ @return_status = ]
      { module_name [ ;number ] | @module_name_var } 
        [ [ @parameter = ] { value 
                           | @variable [ OUTPUT ] 
                           | [ DEFAULT ] 
                           }
        ]
      [ ,...n ]
      [ WITH <execute_option> [ ,...n ] ]
    }
[;]

The documentation is not currently that clear on an acceptable format for value but it seems to be only "simple" expressions such as literal values or @@ prefixed system functions (such as @@IDENTITY). Other system functions such as SCOPE_IDENTITY() are not permitted (even those which do not require parentheses such as CURRENT_TIMESTAMP are not allowed).

So for the time being you need to use syntax such as the below

DECLARE @pID INT;

SET @pID = 1;

/*If 2008+ for previous versions this needs to be two separate statements*/
DECLARE @string VARCHAR(50) = 'Could not find given id: ' + CAST(@pID AS VARCHAR(11))

EXEC WriteLog
  'Component',
  'Source',
  @string 

回答2:

DECLARE @pID int;
declare @IdAsString varchar(100)

SET @pID = 1;

Select @IdAsString ='Could not find given id: ' + Cast(@pId as varchar(10))

EXEC WriteLog 'Component', 'Source', @IdAsString

As pointed out by Martin, the following only applies to columns not variables.

Note that I have amended your cast to varchar(10) this will allow for integers larger than 1 digit. varchar will only allow 1 character

回答3:

You can't do operations on the parameters of a stored procedure. You should assign that value on another variable and then pass it to your SP.

DECLARE @pID int, @nameId VARCHAR(100);
SET @pID = 1;
SET @nameId = 'Could not find given id: ' + CAST(@pID AS varchar);

EXEC WriteLog 'Component', 'Source', @nameId

回答4:

Perhaps something like this?

DECLARE @pID int;
SET @pID = 1;

DECLARE @Message NVARCHAR(50);

SET @Message = 'Could not find given id: ' + CAST(@pID AS varchar)
EXEC WriteLog 'Component', 'Source', @Message;

回答5:

Try this instead...

DECLARE @pID int;
SET @pID = 1;

DECLARE @message varchar(255);
SET @message = 'Could not find given id: ' + CAST(@pID AS varchar)

EXEC WriteLog 'Component', 'Source', @message;

回答6:

DECLARE @id int

SET @id = 10

SELECT LTRIM(RTRIM(STR(@id))) AS stringValue

回答7:

Use this code to print a Sql Server Error message:

BEGIN TRY  
    -- Generate a divide-by-zero error.  
    SELECT 1/0;  
END TRY  
BEGIN CATCH  
    SELECT  
        ERROR_NUMBER() AS ErrorNumber  
        ,ERROR_SEVERITY() AS ErrorSeverity  
        ,ERROR_STATE() AS ErrorState  
        ,ERROR_PROCEDURE() AS ErrorProcedure  
        ,ERROR_LINE() AS ErrorLine  
        ,ERROR_MESSAGE() AS ErrorMessage;  
END CATCH;  
GO  

Here is the result set.

Copy
-----------

(0 row(s) affected)

ErrorNumber ErrorSeverity ErrorState  ErrorProcedure  ErrorLine  ErrorMessage
----------- ------------- ----------- --------------- ---------- ----------------------------------
8134        16            1           NULL            4          Divide by zero error encountered.

(1 row(s) affected)