execute(' INSERT INTO {{%usernames_history}} (account_id, username, applied_in) SELECT id as account_id, username, created_at as applied_at FROM {{%accounts}} '); $this->createIndex('applied_in', '{{%usernames_history}}', 'applied_in'); $this->createIndex('username', '{{%usernames_history}}', 'username'); } public function safeDown() { $this->dropIndex('applied_in', '{{%usernames_history}}'); $this->dropIndex('username', '{{%usernames_history}}'); $this->execute(' DELETE FROM {{%usernames_history}} WHERE id IN ( SELECT t1.id FROM ( SELECT id, MIN(applied_in) FROM {{%usernames_history}} GROUP BY account_id ) t1 ) '); } }