Support for adding a column if it doesn't exist

Dialect

MySQL

Failing SQL

SELECT count(*) INTO @EXIST
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_SCHEMA = 'mydatabase'
  AND COLUMN_NAME = 'mycolumn'
  AND TABLE_NAME = 'mytable' LIMIT 1;

SET @query = IF (@exist <= 0, 'ALTER TABLE mydatabase.`mytable`  ADD COLUMN `mycolumn` MEDIUMTEXT NULL',
    'select \' COLUMN EXISTS\' status');
PREPARE stmt FROM @query;
EXECUTE stmt;

Description

I'm trying to write my migration files in a repeatable manner (So I don't have to create a new migration version EVERY time I need to make a change), but I can't seem to do this when altering a table when adding a column or adding an index. I don't necessarily need to do it in the above way, but I do think this should be supported some way.

Start by reproducing the MySQL migration shown in the issue and inspect how the project parses ALTER TABLE statements. No repository files or tests are named; done should include defined support for repeatable column and index additions, with coverage for the relevant MySQL syntax.