Alphanumeric and Special Character Validation

Create Function fn_ValidateString
(
--RETURN 1 - VALIDE
--       0 - FAILURE
@InputString Varchar(25),
@Type int -- =0 allowes only ALPHANUMERIC, <>0 ALPHANUMERIC AND @  (  ) _ -

)
/*
Author : Ramesh Kondaparthy
Version: Initial
*/Returns int
AS
BEGIN
DECLARE @Status int
DECLARE @Source Varchar(25)
DECLARE @Character CHAR(1)
DECLARE @rowCnt CHAR(1)

SET @Source=@InputString
SET @Character =''

SET @Source = LTRIM(RTRIM(@Source))
DECLARE @MyTable Table (Val char(1))

DECLARE @Pos  INT
DECLARE @Len INT
SET @Pos = 0
SET @Len = 0


SET @Pos = LEN(@Source)
SET @Len = @Pos

WHILE @Pos > 0
BEGIN
SET @Character = LEFT(@Source,1)
--Print @Character

INSERT INTO @MyTable VALUES (@Character)

SET @Pos = @Pos - 1
SET @Source = RIGHT(@Source, @Pos)

END
--Select @Pos

IF @Type = 0
Begin
Select  @rowCnt  = @Len  - count(*) from @MyTable Where Val like '[A-Z]' or Val like '[a-z]' or Val like '[0-9]' 
End
Else
Begin
Select  @rowCnt  = @Len  - count(*) from @MyTable Where Val like '[A-Z]' or Val like '[a-z]' or Val like '[0-9]'  or Val='@'  or Val='('  or Val=')'  or Val='_'  or Val='-'  
End

If @rowCnt <>0 --Print 'FAILURE'
SET @Status  = 0
Else --PRINT 'SUCCESS'
SET @Status  = 1

RETURN(@Status )
End