MySQL - Massive structural changes

I'm working with a database that has links in almost every table to the "user" table to keep track of things like who last created or updated a record. Unfortunately, the primary key of the user table is "username" and not an auto-incrementing identifier. We have frequent situations where the username needs to be changed due to typos or changes in the user profile, and this really takes a long time in the current project.

I want to change the structure to use auto-incremented id, but I can't find an easy way to do it. In SqlServer, I could use a combination of link, cursor, and structural change introspection to do this effortlessly. But from what I've read about MySQL, I (1) can only use loops from ININ in a stored procedure and (2) can only modify a structure from an OUTSIDE stored procedure.

The only option I found was a rather tedious task (1) Create a temporary table to look up username references:

CREATE TEMPORARY TABLE IF NOT EXISTS username_refs as (select table_name, column_name, constraint_name, referenced_table_name, referenced_column_name from information_schema.key_column_usage where REFERENCED_TABLE_NAME = 'user' and referenced_column_name = 'username');

      

        
        
        
      

    

(2) Create a set of SQL statements for each task. For example, this creates a "shadow" column in each table that references the user's name:

select CONCAT('ALTER TABLE `', table_name, '` ADD COLUMN `', column_name,'_2` bigint(20) ;') from username_refs;

      

        
        
        
      

    

This results in hundreds of sql lines. Is there an easier way to do this that I'm just missing?