创建触发器更新 SQL table

Create trigger update SQL table

我想创建触发器更新 table khohang 和 table Dothan

这是我的SQL:

CREATE TRIGGER trigger_update on dathang
AFTER UPDATE AS
BEGIN
 UPDATE khohang INNER JOIN dathang on khohang.mahang =dathang.mahang
    SET khohang.soluong = khohang.soluong - (SELECT soluong FROM dathang where khohang.mahang = dathang.mahang)
END

触发器在 table 上执行(BEFORE/AFTER 插入、更新、删除)操作时发生,因此触发器在该操作上触发并在相同或不同的 [=17] 上执行某些操作=]. 这是 Trigger

的格式
DELIMITER $$

USE `database_name`$$

DROP TRIGGER  `Tigger_name`$$

CREATE 
    TRIGGER `Tigger_name` BEFORE/AFTER INSERT /UPDATE/DELETE ON `Table_1` /* trigger fire from this table*/
    FOR EACH ROW BEGIN
        /* (query) action perform */ 
        update table_2 set field_1="value" where table_2.id=New.field_1; /*New.field_1 is refrance Table_1.field_1. which record effect by action*/
    END;
$$

DELIMITER ;

参考:https://dev.mysql.com/doc/refman/8.0/en/trigger-syntax.html