如何在FlinkSQL中创建和使用自定义UDTF？

https://www.80wz.com/zb_users/upload/2025/05/20250528095009174839700990413.txt

// 通过TableEnvironment注册（Java代码）
StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
StreamTableEnvironment tableEnv = StreamTableEnvironment.create(env);
// 注册为临时函数
tableEnv.createTemporarySystemFunction("user_session", UserSessionUDTF.class);

-- 生成用户会话信息
SELECT 
  user_id,
  session_id,
  session_start,
  event_time,
  action
FROM user_actions
CROSS JOIN LATERAL TABLE(user_session(user_id, action, event_time));