Older pattern for idempotent alter scripts

oldIdempotentAlter.sql

SELECT count(*)
INTO @exist
FROM information_schema.columns 
WHERE table_schema = 'databaseName'
and COLUMN_NAME = 'columnName'
AND table_name = 'tableName';

set @query = IF(@exist <= 0, 
'alter table whatever', 
'select \'Column already exists\' status');

prepare stmt from @query;
EXECUTE stmt;