How to make an existing column NOT NULL in SQL

Backend Development
1

Hi I’m trying to make an exiting column galaxy_id in the galaxy table NOT NULL so that i can set it as a primary key, but I cant figure out how to do that.

I’ve read somwhere that you cant make an empty column NOT NULL so I’ve populated it with one row but that didn’t help.

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2

Figured it out, its “ALTER TABLE galaxy ALTER COLUMN galaxy_id SET NOT NULL” so you can’t enter data type into that command e.g. “ALTER TABLE galaxy ALTER COLUMN galaxy_id INT SET NOT NULL”