MySQL“更新时间戳”列 - 触发器

Question

I'm adding a column tsu (timestamp update) of type DATETIME to a number of my tables.

I need to write BEFORE UPDATE triggers that will update the column to CURRENT_TIMESTAMP() , but I can't get it right. Tried:

DELIMITER $$
CREATE
    TRIGGER `cams`.`tsu_update_csi` BEFORE UPDATE
    ON `cams`.`csi`
    FOR EACH ROW BEGIN
        UPDATE csi SET tsu = CURRENT_TIMESTAMP WHERE csi_code = OLD.csi_code;
    END$$
DELIMITER ;

Can anyone point me in the right direction pls? MTIA

Answer 1

Okay, try this one:

DELIMITER $$ CREATE  
    TRIGGER `cams`.`tsu_update_csi` BEFORE UPDATE  
    ON `cams`.`csi`  
      FOR EACH ROW BEGIN  
        SET NEW.tsu = CURRENT_TIMESTAMP;   
END$$ DELIMITER ;

Answer 2

If the field can be defined as a timestamp, you can use the following:

 ts2 TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP);

Answer 3

不知道它是否适合您，但您始终可以将其设为没有默认值的TIMESTAMP字段——MySQL 会在每次更新时自动将表中定义的第一个此类字段的值设置为当前时间戳。

Answer 4

ts2 CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP works for DATETIME and TIMESTAMP fields, for one and multiple fields

so you can use datecreated CURRENT_TIMESTAMP (as the default value)

and dateupdated CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP works for DATETIME and TIMESTAMP fields (as the default value)

You can use the above as SQL commands or default values in MySQL workbench

Answer 5

There are a lot of non-working or incomprehensible examples on the network. I spent several hours to put together a working example for my EFFCORE CMS. Here is this example:

Trigger on UPDATE

DELIMITER ;;
CREATE TRIGGER `updated_at__on_update`
BEFORE UPDATE
ON `demo`
FOR EACH ROW
BEGIN
   SET new.updated_at = UNIX_TIMESTAMP();
END;;
DELIMITER ;

Trigger on INSERT

DELIMITER ;;
CREATE TRIGGER `updated_at__on_insert`
BEFORE INSERT
ON `demo`
FOR EACH ROW
BEGIN
   SET new.updated_at = UNIX_TIMESTAMP();
END;;
DELIMITER ;

Table demo

CREATE TABLE `demo` (
    `id` int NOT NULL AUTO_INCREMENT,
    `text` varchar(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci DEFAULT NULL,
    `updated_at` int NOT NULL DEFAULT '0',
    PRIMARY KEY (`id`)
);