Insert or update user data I inherited an application that uses some stored procedures. Here is a sample of one of the stored procedures used to insert or modify user data.

would like to get the group's opinion on the code. The SQL Server version is Microsoft SQL Server 2014 - 12.0.4100.1 (X64).

USE [MyDataBase]
GO
/****** Object:  StoredProcedure [dbo].[InsertOrModifyUserData]    Script Date: 2/2/2016 8:39:57 PM ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO

ALTER  PROCEDURE [dbo].[InsertOrModifyUserData]
@userName NVARCHAR(200),
@isSuperAdmin BIT = NULL,
@modifiedBy NVARCHAR(200),
@modifiedDate DATETIME = NULL,
@isActive BIT = NULL
AS

BEGIN
    SET NOCOUNT ON;    
    SET XACT_ABORT ON; 
    BEGIN TRY
        BEGIN TRANSACTION


            IF (@modifiedDate IS NULL OR @modifiedDate ='1900-01-01 00:00:00.000')
                SET @modifiedDate = GETDATE()
            IF (@isActive IS NULL)
                SET @isActive = 1


            IF ((@userName IS NOT NULL OR @userName &lt;&gt;'') AND (@isSuperAdmin IS NOT NULL OR @isSuperAdmin&lt;&gt;'') AND (@modifiedBy IS NOT NULL OR @modifiedBy &lt;&gt;''))
            BEGIN 
                IF EXISTS(SELECT UserName FROM [dbo].[UserAccess] WHERE UserName = @userName)
                    UPDATE  [dbo].[UserAccess]  
                        SET IsSuperAdmin    = @isSuperAdmin,
                            ModifiedBy      = @modifiedBy,
                            ModifiedDate    =   @modifiedDate,
                            IsActive        = @isActive 
                    WHERE   UserName = @userName    
                ELSE
                    INSERT INTO [dbo].[UserAccess] (UserName, IsSuperAdmin, CreatedDate, ModifiedBy, ModifiedDate,IsActive)
                    VALUES(@userName, @isSuperAdmin, GETDATE(), @modifiedBy, @modifiedDate, @isActive)  

            END 
        ELSE
            RAISERROR('Required parameters are not provided or Required parameters are passed as NULL',13,1)
        COMMIT TRANSACTION
        select null
    END TRY
    BEGIN CATCH
            DECLARE @ErrorMessage NVARCHAR(MAX) = ERROR_MESSAGE();
            DECLARE @ErrorSeverity INT = ERROR_SEVERITY();
            DECLARE @ErrorState INT = ERROR_STATE();
            RAISERROR(@ErrorMessage, @ErrorSeverity, @ErrorState);
            ROLLBACK TRANSACTION;
    END CATCH;

END
Dead code
In this:

    COMMIT TRANSACTION
    select null
END TRY


This line of code: select null does nothing useful (read: nothing at all) and should be deleted. I have no idea why it is there to begin with, but querying for NULL with no criteria will always be null.

Errors not useful
You could improve this error reporting:

    ELSE
        RAISERROR('Required parameters are not provided or Required parameters are passed as NULL',13,1)


TLDR: Don't filter error logs, just store stuff. Developers can filter them easily if they need to.
Why? As it is, this is raising an error with no information on &quot;why&quot; the error was raised. At the very least return the input parameters so the user/dev can decipher what is wrong. This is especially relevant if you are logging those errors somewhere.
You would want to include as much relevant information as possible in your errors, especially if there are multiple instances and databases involved. There are few things which hinder improvement and bug fixes more than half-arsed error logs. Log everything and let the developers sort it out.