INSERT UPDATE Stored Procedure

CREATE PROCEDURE [dbo].[USP_MM_INSUPDUserDetails] (
           @UserDetailID int=0,  --if zero the new record otherwise update
           @UserID int=0, --if zero then new record
           @FirstName varchar(50),
           @LastName varchar(50),
           @Address1 varchar(500),
           @Address2 varchar(500)=null,
           @CityId int,
           @StateId int,
           @ZipCode nvarchar(50),
           @CountryId int,
           @Phone varchar(20),
           @EmailID nvarchar(50),
           @AlternateEmailID nvarchar(50),
           @DateOfBirth datetime,
           @UserTypeID int,
        @UserName    varchar(50),
        @Password    varchar(50),
        @SeccretQuestion_ID    int,
        @Secret_Answer    varchar(500),
        @IsAccountActive    bit
        --@Account_Active_Code    int  --will be implemented later when email func is implemented
)
   

AS
BEGIN
    -- SET NOCOUNT ON added to prevent extra result sets from
    -- interfering with SELECT statements. TBL_MM_User_Details
    SET NOCOUNT ON;

    if(@UserID<>0)
    BEGIN
    if exists( Select UserName from TBL_MM_User_Info where UserName=@UserName)
    BEGIN
     update TBL_MM_User_Info
      set Password=@Password,
        SeccretQuestion_ID=@SeccretQuestion_ID,
        Secret_Answer=@Secret_Answer,
        IsAccountActive=@IsAccountActive
    WHERE UserName=@UserName
    UPDATE TBL_MM_User_Details
    SET
FirstName=@FirstName,
LastName=@LastName,
Address1=@Address1,
Address2=@Address2,
ZipCode=@ZipCode,
CountryId=@CountryId,
Phone =@Phone,
EmailID=@EmailID,
AlternateEmailID=@AlternateEmailID,
DateOfBirth=@DateOfBirth,
UserTypeID=@UserTypeID
 where UserDetailID=@UserDetailID
    END
    END

ELSE
BEGIN
    INSERT INTO TBL_MM_User_Info(UserName,Password,SeccretQuestion_ID,Secret_Answer,IsAccountActive)
    VALUES(@UserName,@Password,@SeccretQuestion_ID,@Secret_Answer,@IsAccountActive)
    Select @UserID=UserID from TBL_MM_User_Info where UserName=@UserName

    INSERT INTO TBL_MM_User_Details (

     FirstName,LastName,Address1,Address2,ZipCode,Phone,EmailID,AlternateEmailID,DateOfBirth,
     UserTypeID,userID )
     VALUES (@FirstName,@LastName,@Address1,@Address2,@ZipCode,@Phone,@EmailID,@AlternateEmailID,
     @DateOfBirth,@UserTypeID,@userID
    )
    END

END