text: CREATE TABLE IF NOT EXISTS group_access (
    group_id          CHAR(16)  NOT NULL,
    user_id           CHAR(16)  NOT NULL,
    access_grant_time TIMESTAMP NOT NULL DEFAULT NOW(),
  
    CONSTRAINT fk_group_access_group
      FOREIGN KEY (group_id)
        REFERENCES app_group(id)
          ON DELETE CASCADE,
  
    CONSTRAINT fk_group_access_user
      FOREIGN KEY (user_id)
        REFERENCES app_user(id)
          ON DELETE CASCADE
  );
  