Return BEFORE UPDATE 触发器中的单个 SELECT 行

Question

To alter the row to be stored, it is possible to replace single values directly in NEW and return the modified NEW, or to build a complete new record/row to return.

我想做后者。我有一个 SELECT 保证 return 一行。如何使用？

Answer 1

这是一个示例：

CREATE TABLE sample (
   id integer PRIMARY KEY,
   sthg text NOT NULL,
   ip inet
);

CREATE FUNCTION sample_trig() RETURNS trigger
   LANGUAGE plpgsql AS
$$BEGIN
   SELECT 42, 'yes!', '127.0.0.1'::inet INTO NEW;
   RETURN NEW;
END;$$;

CREATE TRIGGER sample_trig
   BEFORE INSERT ON sample FOR EACH ROW
   EXECUTE PROCEDURE sample_trig();

INSERT INTO sample VALUES (1, 'new', NULL);

TABLE sample;

 id | sthg |    ip     
----+------+-----------
 42 | yes! | 127.0.0.1
(1 row)

Return BEFORE UPDATE 触发器中的单个 SELECT 行

Return single SELECT row in BEFORE UPDATE trigger

postgresql

database-trigger