如何将MySQL触发器异常/失败信息存储到表或变量中

问题描述

我被困在某个地方，需要您的帮助.

I am stuck at somewhere and I need some help from you.

我有两个数据库，即test_db1和test_db2，并且在两个数据库上都有users表.两个数据库最初都是空的(0行).

I have two databases i.e., test_db1 and test_db2 and have users table on both of them. Both databases initially are empty (0 rows).

这是users表模式:

DROP TABLE IF EXISTS `users`;
CREATE TABLE `users` (
  `id` int(11) AUTO_INCREMENT,
  `name` varchar(30) NOT NULL,
  `age` int(11) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;

之后，我在test_db1.users表上为INSERT，UPDATE和DELETE事件编写了一些触发器，以下是每个触发器的作用:

After that, I have written some triggers for INSERT, UPDATE and DELETE events on test_db1.users table, Below is what each trigger does:

• 在test_db1.users中的INSERT上，在test_db2.users
中插入同一行在test_db1.users中UPDATE上的
• ，在test_db2.users
中更新同一行
• 在test_db1.users中的DELETE上，从test_db2.users
中删除同一行

• on INSERT in test_db1.users, insert same row in test_db2.users
• on UPDATE in test_db1.users, update same row in test_db2.users
• on DELETE in test_db1.users, delete same row from test_db2.users

这是触发代码段.

DELIMITER //

-- TRIGGER FOR INSERT
DROP TRIGGER IF EXISTS `test_db1_users_bi`;
CREATE TRIGGER `test_db1_users_bi` BEFORE INSERT ON `users` FOR EACH ROW 
BEGIN
    INSERT INTO `test_db2`.`users` (id, name, age) VALUES (NEW.id, NEW.name, NEW.age);
END; //

-- TRIGGER FOR UPDATE
DROP TRIGGER IF EXISTS `test_db1_users_bu`;
CREATE TRIGGER `test_db1_users_bu` BEFORE UPDATE ON `users` FOR EACH ROW 
BEGIN
    UPDATE `test_db2`.`users`
        SET name = NEW.name,
            age = NEW.age
        WHERE id = NEW.id;
END; //

-- TRIGGER FOR DELETE
DROP TRIGGER IF EXISTS `test_db1_users_bd`;
CREATE TRIGGER `test_db1_users_bd` BEFORE DELETE ON `users` FOR EACH ROW 
BEGIN
    DELETE FROM `test_db2`.`users`
        WHERE id = OLD.id;
END; //

-- DELIMITER;

现在，问题！

当前，它在触发器中没有定义任何错误/异常处理程序..因此，我也想处理该错误/异常处理程序，但我不知道该怎么做.我只是不知道如何获取异常及其异常之类的属性-错误代码，错误消息?

Currently, this doesn't have any errors/exceptions handlers defined in triggers.. So, I want to handle that too but I don't know how to do that. I just don't know how would I get the exception and it's properties like exceptions - error code, error message?

我只想将捕获的异常/错误从每个触发器(如果失败)存储到test_db1.errors表中:

I just want to store the caught exception/error into test_db1.errors table from each of the trigger (if fails):

这是errors表架构，如下所示:

Here's errors table schema something looks like:

DROP TABLE IF EXISTS `errors`;
CREATE TABLE `errors` (
  `id` int(11) AUTO_INCREMENT,
  `error_code` varchar(30) DEFAULT NULL,
  `error_message` TEXT DEFAULT NULL,
  `emailed` TINYINT DEFAULT 0,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;

仅供参考:以下是可能的失败:

FYI: Below are the possible failures:

• 如果test_db2不存在或无法连接?
• 如果INSERT触发器失败，即是什么原因?
• 如果UPDATE触发器失败，即是什么原因?
• 如果DELETE触发器失败，即是什么原因?

• If test_db2 is not there or unable to connect?
• If INSERT trigger fails i.e., whatever the reason?
• If UPDATE trigger fails i.e., whatever the reason?
• If DELETE trigger fails i.e., whatever the reason?

如果有人可以，请让我知道如何获取异常及其错误代码，错误消息的属性，并将其存储到触发器内部的变量中，以便执行插入操作以将其存储到表中?

If anyone can Just let me know how can I get the exception and it's properties like error code, error message and store it to variables from inside triggers so that then I will perform insert to store them into table?

我正在运行MySQL版本:5.5 +

I am running MySQL version: 5.5+

谢谢！

推荐答案

我通过DECLARE CONTINUE HANDLER和GET DIAGNOSTICS CONDITION找到了一个黑客，所以我想，我必须在这里分享它.

I found a hack via DECLARE CONTINUE HANDLER and GET DIAGNOSTICS CONDITION, so just thought, I must share it here.

这是我完整的最终脚本，该脚本使两个数据库users表保持备份(同步)，这意味着test_db1(我们可以将其称为productionDB)上的任何更新都将在test_db2上进行(我们可以将其称为stagingDB):

Here's my complete final script which keeps backup (sync) for both databases users table what it means is that any update on test_db1 (which we may call it as a productionDB) will occur on test_db2 (which we may call it to as stagingDB):

/*
Create two databases:
    1. `test_db1`
    2. `test_db2`
and execute below create *Table script* on both databases.
after that execute *Triggers Script* on `test_db1` only..
*/

/*
    TABLE STRUCTURE FOR `users`
*/

DROP TABLE IF EXISTS `users`;
CREATE TABLE IF NOT EXISTS `users` (
  `id` int(11) AUTO_INCREMENT NOT NULL,
  `name` varchar(30) NOT NULL,
  `age` int(11) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;

/*
    TABLE STRUCTURE FOR `errors`
*/

DROP TABLE IF EXISTS `errors`;
CREATE TABLE IF NOT EXISTS `errors` (
  `id` int(11) AUTO_INCREMENT NOT NULL,
  `code` varchar(30) NOT NULL,
  `message` TEXT NOT NULL,
  `query_type` varchar(50) NOT NULL,
  `record_id` int(11) NOT NULL,
  `on_db` varchar(50) NOT NULL,
  `on_table` varchar(50) NOT NULL,
  `emailed` TINYINT DEFAULT 0,
  `created_at` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;

/*
    TRIGGERS SCRIPTS FOR INSERT, UPDATE AND DELETE OPERATIONS
*/

DELIMITER //

-- TRIGGER FOR INSERT
DROP TRIGGER IF EXISTS `test_db1_users_ai`;
CREATE TRIGGER `test_db1_users_ai` AFTER INSERT ON `users` FOR EACH ROW 
BEGIN
    -- Declare variables to hold diagnostics area information
    DECLARE errorCode CHAR(5) DEFAULT '00000';
    DECLARE errorMessage TEXT DEFAULT '';

    -- Declare exception handler for failed insert
    DECLARE CONTINUE HANDLER FOR SQLEXCEPTION 
    BEGIN
      GET DIAGNOSTICS CONDITION 1
        errorCode = RETURNED_SQLSTATE, errorMessage = MESSAGE_TEXT;
    END;

    -- Perform the insert
    INSERT INTO `test_db2`.`users` (id, name, age) VALUES (NEW.id, NEW.name, NEW.age);

    -- Check whether the insert was successful
    IF errorCode != '00000' THEN
        INSERT INTO `errors` (code, message, query_type, record_id, on_db, on_table) VALUES (errorCode, errorMessage, 'insert', NEW.id, 'test_db2', 'users');
    END IF;
END; //

-- TRIGGER FOR UPDATE
DROP TRIGGER IF EXISTS `test_db1_users_au`;
CREATE TRIGGER `test_db1_users_au` AFTER UPDATE ON `users` FOR EACH ROW 
BEGIN
    -- Declare variables to hold diagnostics area information
    DECLARE errorCode CHAR(5) DEFAULT '00000';
    DECLARE errorMessage TEXT DEFAULT '';

    -- Declare exception handler for failed insert
    DECLARE CONTINUE HANDLER FOR SQLEXCEPTION 
    BEGIN
      GET DIAGNOSTICS CONDITION 1
        errorCode = RETURNED_SQLSTATE, errorMessage = MESSAGE_TEXT;
    END;

    -- Perform the update
    UPDATE `test_db2`.`users`
        SET name = NEW.name,
            age = NEW.age
        WHERE id = NEW.id;

    -- Check whether the update was successful
    IF errorCode != '00000' THEN
        INSERT INTO `errors` (code, message, query_type, record_id, on_db, on_table) VALUES (errorCode, errorMessage, 'update', NEW.id, 'test_db2', 'users');
    END IF;
END; //

-- TRIGGER FOR DELETE
DROP TRIGGER IF EXISTS `test_db1_users_ad`;
CREATE TRIGGER `test_db1_users_ad` AFTER DELETE ON `users` FOR EACH ROW 
BEGIN
    -- Declare variables to hold diagnostics area information
    DECLARE errorCode CHAR(5) DEFAULT '00000';
    DECLARE errorMessage TEXT DEFAULT '';

    -- Declare exception handler for failed insert
    DECLARE CONTINUE HANDLER FOR SQLEXCEPTION 
    BEGIN
      GET DIAGNOSTICS CONDITION 1
        errorCode = RETURNED_SQLSTATE, errorMessage = MESSAGE_TEXT;
    END;

    -- Perform the delete
    DELETE FROM `test_db2`.`users`
        WHERE id = OLD.id;

    -- Check whether the insert was successful
    IF errorCode != '00000' THEN
        INSERT INTO `errors` (code, message, query_type, record_id, on_db, on_table) VALUES (errorCode, errorMessage, 'delete', OLD.id, 'test_db2', 'users');
    END IF;
END; //

-- DELIMITER;

希望这对其他人来这里有帮助.

Hope this will help others when they come over here.

干杯

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