text: create table user_notification(
  		notification_id VARCHAR(36) NOT NULL PRIMARY KEY,
  		notification_type int,
          user_id VARCHAR(36) NOT NULL,
          pet_id VARCHAR(36),
          event_id VARCHAR(36),
          created_at timestamp,
          payload VARCHAR(1024),
          has_read boolean,
          FOREIGN KEY (user_id) REFERENCES users(id) ON DELETE CASCADE,
          FOREIGN KEY (pet_id) REFERENCES pet(id)
  );
  
  