By default, new columns are added to the end of a table in MySQL. This works
well most of the time, but sometimes when you’re retrofitting a column into a
table, you may want it to be adjacent columns closer to the start of the table.
The ALTER statement makes it easy to add a column anywhere in a table, by
adding AFTER at the end of the ADD COLUMN query. A query adding a single
column after another column looks like this:
ALTER TABLE `table`
ADD COLUMN `new_column` VARCHAR(255) NOT NULL
AFTER `existing_column`
You can adjust the column definition however you see fit.
This also works if you’re adding multiple columns, even allowing you to
reference columns you’re about to add and not just columns that already exist on
the table:
ALTER TABLE `table`
ADD COLUMN `new1` VARCHAR(255) NOT NULL AFTER `existing`,
ADD COLUMN `new2` VARCHAR(255) NOT NULL AFTER `new1`
