为PL/pGSQL

Question

我用于此问题的表是

  Table "table.group_standings"
    Column |         Type          | Modifiers
   --------+-----------------------+-----------
    team   | character varying(25) | not null
    wins   | smallint | not null   
    losses | smallint | not null
    draws  | smallint | not null
    points | smallint| not null
   Indexes:
     "group_standings_pkey" PRIMARY KEY, btree (team)
  Check constraints:
   "group_standings_draws_check" CHECK (draws >= 0)
   "group_standings_losses_check" CHECK (losses >= 0)
   "group_standings_points_check" CHECK (points >= 0)
   "group_standings_wins_check" CHECK (wins >= 0)

我现在拥有的代码，我需要帮助来告诉用户他们不允许更改团队名称，但是我遇到了问题。

 CREATE OR REPLACE FUNCTION disallow_team_name_update() RETURNS trigger AS $$
    BEGIN
            if(NEW.team <> OLD.team)
            /*tell the user to not change team names*/
           
    END;
$$ LANGUAGE plpgsql;


CREATE TRIGGER tr_disallow_team_name_update BEFORE INSERT OR UPDATE OF team ON group_standings 
FOR EACH ROW EXECUTE PROCEDURE disallow_team_name_update();

您需要RAISE

Answer 1

才能提出例外。手册中有例子。

RAISE EXCEPTION ....

（这看起来像功课，您以前曾问过有关作业的问题，所以我故意没有给出完整的答案）。