mysql - 触发器从 plpgSQL 到 MySQL

Question

我对触发器有疑问。 我已经在 plpgSQL 中为 PostgreSQL 创建了一个函数，但是，现在我需要在 MySQL 中执行此操作。我几乎尝试了一切，但我不知道该怎么做。有人知道该怎么做并帮助我吗？

这是plpgSQL中的代码:

CREATE OR REPLACE FUNCTION provjera_rezultata() RETURNS TRIGGER AS $$
    DECLARE
    neodigrane_utakmice INT;

    BEGIN
    SELECT COUNT(*) INTO neodigrane_utakmice
    FROM utakmice AS u
        JOIN momcadi AS m1
            ON m1.momcad_ID = u.momcad_a
        JOIN momcadi AS m2
            ON m2.momcad_ID = u.momcad_b
    WHERE rezultat IS NULL;

    IF neodigrane_utakmice > 0 THEN
        RAISE NOTICE 'Broj utakmica bez rezultata je %', neodigrane_utakmice;
    END IF;

    RETURN NEW;
    END;
$$ LANGUAGE plpgsql;

此外，我不知道在 MySQL 中使用什么来处理来自 PostgreSQL 的“RAISE NOTICE”。

我这样做了，但是我得到了错误:(

DELIMITER $$

CREATE TRIGGER provjera_rezultata
    AFTER INSERT ON utakmice FOR EACH ROW
    DECLARE broj INTEGER;

BEGIN
    SELECT COUNT(*) INTO broj
    FROM utakmice AS u
        JOIN momcadi AS m1
            ON m1.momcad_ID = u.momcad_a
        JOIN momcadi AS m2
            ON m2.momcad_ID = u.momcad_b
    WHERE rezultat IS NULL;

    IF broj > 0 THEN
        SIGNAL SQLSTATE '45000'
        SET MESSAGE_TEXT = 'Postoje utakmice bez konacnog rezultata!';
    END IF;
END $$

Answer 1

您的代码的内部部分可以基本保持不变。

触发器是用 CREATE TRIGGER 创建的.

通知在 MySQL 中称为 signals .你做

SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = 'An error occurred';