Aynı ID İle Tekrar Girmeme Sorunu

Kod:
CREATE PROCEDURE ACCOUNT_LOGIN
-- Edit Voix
@AccountID varchar(21),
@Password varchar(13),
@nRet smallint OUTPUT

AS


select @nRet=count(*) from tb_user where straccountid=@AccountID
if @nRet=0
begin
insert into tb_user values (@AccountID , @Password , 1 , 6 , 1 ,1)
set @nRet=1
RETURN
end


DECLARE @tahsin tinyint, @myko smallint, @account int, @login int , @procedure int
SET @tahsin = 0
SET @myko = 0

DECLARE @pwd varchar(13)

SET @pwd = null

IF @pwd <> @Password
BEGIN
SET @nRet = 3
RETURN
END

IF @login=0
begin
set @nRet=11
RETURN
end
IF @account = 0
begin
set @nRet=12
RETURN
end
IF @procedure=0
begin
set @nRet=4
RETURN
end

select @nRet=count(*) from currentuser where straccountid=@AccountID

IF @nRet>0
begin
set @nRet=5
RETURN
end



SELECT @tahsin = bNation, @myko = bCharNum FROM ACCOUNT_CHAR WHERE strAccountID = @AccountID
IF @@ROWCOUNT = 0
BEGIN
SET @nRet = 1
RETURN
END
IF @myko = 0
BEGIN
SET @nRet = 1
RETURN
END
ELSE
BEGIN
SET @nRet = 1
RETURN
END
GO