Question

Please suppose that in SQL Server 2005, if you launch the following query:

SELECT CHICKEN_CODE FROM ALL_CHICKENS WHERE MY_PARAMETER = 'N123123123';

you obtain:

31

as result.

Now, I would like to write a function that, given a value for MY_PARAMETER, yields the corresponding value of CHICKEN_CODE, found in the table ALL_CHICKENS.

I have written the following stored function in SQL Server 2005:

ALTER FUNCTION [dbo].[determines_chicken_code]
(
    @input_parameter                         VARCHAR 
)
RETURNS varchar
AS 
BEGIN
    DECLARE @myresult varchar

    SELECT @myresult  =  CHICKEN_CODE
    FROM dbo.ALL_CHICKENS
    WHERE MY_PARAMETER = @input_parameter

    RETURN @myresult
END

But if I launch the following query:

SELECT DBO.determines_chicken_code('N123123123') 

it yields:

NULL

Why?

Thank you in advance for your kind cooperation.

Answer 1

define the length of your varchar variables like this

varchar(100)

Without the 100 (or whatever length you choose) its lengh is 1 and the where clause will filter out the correct results.