How to copy over values from one column to another newly added column?

Question

I am working on a web application that is up and running on a production server. I need to make some changes to the database but I am not sure what is the best way to go about this.

I have a table called Trips and it contains columns "maximum_guests", "minimum_guests", etc.

I need to add a column called "base_guests" and I want to give it a value of "maximum_guests" for existing entries in my table(production data). From this point forward Trips will only be created if both "base_guests" and "maximum_guests" are provided.

Is there a safe way to do this? I am using Php Symfony, mysql and doctrine if that helps.

Answer 1

You should first make an export of your database just in case. Then add the column to the table and run.

UPDATE Trips set base_guests = maximum_guests;

This will assign the value of maximum_guests to base_guests for each record in the Trips table.