addSql('ALTER TABLE `partition` DROP FOREIGN KEY FK_9EB910E419EB6921'); $this->addSql('ALTER TABLE `partition` ADD CONSTRAINT FK_9EB910E419EB6921 FOREIGN KEY (client_id) REFERENCES client (id) ON DELETE SET NULL'); } public function down(Schema $schema): void { // this down() migration is auto-generated, please modify it to your needs $this->addSql('ALTER TABLE `partition` DROP FOREIGN KEY FK_9EB910E419EB6921'); $this->addSql('ALTER TABLE `partition` ADD CONSTRAINT FK_9EB910E419EB6921 FOREIGN KEY (client_id) REFERENCES client (id)'); } }