text: CREATE TABLE user_group_relations (
      id INTEGER AUTO_INCREMENT NOT NULL PRIMARY KEY,
      group_id INTEGER NOT NULL,
      user_id INTEGER NOT NULL,
      permission JSON
  );
  
  ALTER TABLE user_group_relations ADD INDEX group_user_index(group_id, user_id);
  ALTER TABLE user_group_relations ADD INDEX group_index(group_id);
  ALTER TABLE user_group_relations ADD INDEX user_index(user_id);
  