Question

我在触发器中有递归问题。

我有桌子：

CREATE TABLE employees(
   task int4 NOT NULL,
   first_name varchar(40) NOT NULL,
   last_name varchar(40) NOT NULL,
   PRIMARY KEY (task, cli_id_number)
);

当我插入值时：

(123, name, last)

我想自动插入这些值：

(321, name, last)

我是按照以下方式执行此操作，但显然触发器是递归的，并且在第一次递归后它尝试插入先前插入的值。

CREATE OR REPLACE FUNCTION insert_task() RETURNS trigger AS $BODY$
BEGIN
  IF new.task = '123' AND (
     SELECT cant FROM (
       SELECT name, task, count(*) AS cant
       FROM client_task
       WHERE name = NEW.name AND task = NEW.task
       GOUP BY 1,2
       HAVING count(*) <= 1
     ) t) = 1 THEN
    INSERT INTO client_task(task, name, last_name)
    VALUES('321', NEW.task, NEW.name, NEW.last_name);
    RETURN NEW;
  ELSE 
    IF NEW.task = '321' AND (
      SELECT cant FROM (
        SELECT name, task, count(*) AS cant
        FROM client_task
        WHERE name = NEW.name AND task = NEW.task
        GROUP BY 1, 2
        HAVING count(*) <=1
      ) t) = 1 THEN
      INSERT INTO client_task(task, name, last_name)
      VALUES('123', NEW.task, NEW.name, NEW.last_name);
      RETURN NEW;
    END IF;
  END IF;
  RETURN NULL;
END; $BODY$ LANGUAGE 'plpgsql';

任何帮助表示感谢。

Answer 1

使用pg_trigger_depth()函数返回（as stated in the documentation）：

PostgreSQL触发器的当前嵌套级别（如果未调用则为0，直接或间接地从触发器内部开始）

CREATE TRIGGER insert_task
AFTER INSERT ON employees
FOR EACH ROW
WHEN (pg_trigger_depth() = 0)
EXECUTE PROCEDURE insert_task()

如何避免PostgreSQL中的触发器递归

1 个答案: