在postgresql中创建触发器

我的触发器有问题：

CREATE OR REPLACE FUNCTION process_fillDerivedFrom_used() RETURNS TRIGGER AS $fillDerivedFrom_used$
  DECLARE
    prog      varchar(255);
    current   varchar(255);
  BEGIN
    SELECT u.iduseentity as prog ,g.idCreatedEntity as current
    FROM entity e
    JOIN used u ON e.identity=u.iduseentity
    JOIN activity a ON a.idactivity=u.idusedactivity
    JOIN generatedby g ON g.idcreatoractivity=a.idactivity

    INSERT INTO DERIVEDFROM VALUES (prog,current)
  END;

$fillDerivedFrom_used$ LANGUAGE plpgsql;
CREATE TRIGGER fillDerivedFrom_used
AFTER INSERT OR UPDATE OR DELETE ON emp
    FOR EACH ROW EXECUTE PROCEDURE process_fillDerivedFrom_used();

我使用了3个表，查询是正确的，所以我认为错误不是来自这里。但当我在我的终端中复制超过这个触发器时，什么都没有发生，没有错误消息，我可以在终端中写入，但我不能执行任何查询，就像我忘记了触发器中的某些内容，所以我认为它没有完全被创建

我想我混合了我在学校学过的两种语言PL/SQL和postgresql

---

谢谢你的帮助

我不知道你有什么问题。一个是显而易见的。as不用于变量；进入is。此外，还应命名变量，使其不会与列名冲突：

CREATE OR REPLACE FUNCTION process_fillDerivedFrom_used() RETURNS TRIGGER AS $fillDerivedFrom_used$
  DECLARE
    prog      v_varchar(255);
    current   v_varchar(255);
  BEGIN
    SELECT u.iduseentity as prog, g.idCreatedEntity as current
    INTO v_proc, v_current
    FROM entity e JOIN
         used u
         ON e.identity = u.iduseentity JOIN
         activity a
         ON a.idactivity = u.idusedactivity JOIN
         generatedby g
         ON g.idcreatoractivity = a.idactivity

    INSERT INTO DERIVEDFROM VALUES (v_prog, v_current)
END;

当然，这就引出了为什么要使用变量的问题：

CREATE OR REPLACE FUNCTION process_fillDerivedFrom_used() RETURNS TRIGGER AS $fillDerivedFrom_used$
  BEGIN
    INSERT INTO DERIVEDFROM (prog, current)  -- or whatever the column names are
        SELECT u.iduseentity as prog, g.idCreatedEntity as current
        FROM entity e JOIN
             used u
             ON e.identity = u.iduseentity JOIN
             activity a
             ON a.idactivity = u.idusedactivity JOIN
             generatedby g
             ON g.idcreatoractivity = a.idactivity;    
END;

---

我已经做到了，这是工作，谢谢你的帮助

CREATE OR REPLACE FUNCTION process_fillDerivedFromGenby() RETURNS TRIGGER AS $fillDerivedFromgenby$
  DECLARE
    prog     varchar(255);
    curent   varchar(255);
  BEGIN

    SELECT u.iduseentity , g.idCreatedEntity into prog,curent
    FROM entity e
    JOIN used u ON e.identity=u.iduseentity
    JOIN activity a ON a.idactivity=u.idusedactivity
    JOIN generatedby g ON g.idcreatoractivity=a.idactivity
    WHERE g.idCreatedEntity =NEW.idCreatedEntity;

    --raise notice 'curent: "%" prog by "%"', curent, prog;

    INSERT INTO DERIVEDFROM VALUES(prog,curent);
    return new;
  END;

$fillDerivedFromgenby$ LANGUAGE plpgsql;
CREATE TRIGGER fillDerivedFromgenby AFTER INSERT ON GENERATEDBY
    FOR EACH ROW EXECUTE PROCEDURE process_fillDerivedFromGenby();

---

您应该选择into变量，而不是别名。。。而且，在select之后没有分号，函数的定义看起来很奇怪——您想查询emp？每行上的四个表联接？。。为什么不插入DERIVEDFROM select…all__your_select。。。？。。请记住-您不操作新的或旧的记录在这里-它看起来根本不像触发功能