MySQL 存储过程中的错误处理

MySQL 存储过程中的错误处理实例

第一步：建一个表

CREATE TABLE article_tags(
    article_id INT,
    tag_id     INT,
    PRIMARY KEY(article_id,tag_id)
);

第二步：建立存储过程insert_article_tags

DELIMITER $$

CREATE PROCEDURE insert_article_tags(IN article_id INT, IN tag_id INT)
BEGIN

    DECLARE CONTINUE HANDLER FOR 1062
    SELECT CONCAT('duplicate keys (',article_id,',',tag_id,') found') AS msg;

    -- insert a new record into article_tags
    INSERT INTO article_tags(article_id,tag_id)
    VALUES(article_id,tag_id);

    -- return tag count for the article
    SELECT COUNT(*) FROM article_tags;
END $$

第三步：插入正常数据

CALL insert_article_tags(1,1);
CALL insert_article_tags(1,2);
CALL insert_article_tags(1,3);

第四步：异常数据处理（有主键约束，报错了）

CALL insert_article_tags(1,3);

第五步：测试其他异常及运行级别顺序（）：

DECLARE EXIT HANDLER FOR 1062 
SELECT 'MySQL error code 1062 invoked as  errmsg';

DECLARE EXIT HANDLER FOR SQLSTATE '23000'
SELECT 'SQLSTATE 23000 invoked' as  errmsg;
    
DECLARE EXIT HANDLER FOR SQLEXCEPTION
SELECT 'MySQL error code 1062 invoked as  errmsg';

5.1创建存储过程

DELIMITER $$

CREATE PROCEDURE insert_article_tags_2(IN article_id INT, IN tag_id INT)
BEGIN

    DECLARE EXIT HANDLER FOR SQLEXCEPTION 
    SELECT 'SQLException invoked ' as errmsg;

    DECLARE EXIT HANDLER FOR 1062 
        SELECT 'MySQL error code 1062 invoked'  as errmsg;

    DECLARE EXIT HANDLER FOR SQLSTATE '23000'
    SELECT 'SQLSTATE 23000 invoked'  as errmsg;

    -- insert a new record into article_tags
    INSERT INTO article_tags(article_id,tag_id)
    VALUES(article_id,tag_id);

    -- return tag count for the article
    SELECT COUNT(*) FROM article_tags;
END $$

5.2测试结果

CALL insert_article_tags_2(1,3);

结果为：

MySQL error code 1062 invoked

分别屏蔽存储过程如下insert_article_tags_2中
/* DECLARE EXIT HANDLER FOR SQLEXCEPTION
SELECT 'SQLException invoked ’ as errmsg;*/
/DECLARE EXIT HANDLER FOR 1062
SELECT ‘MySQL error code 1062 invoked’ as errmsg;/
/DECLARE EXIT HANDLER FOR SQLSTATE ‘23000’
SELECT ‘SQLSTATE 23000 invoked’ as errmsg;/
测试最中结果 优先级：【FOR 1062 】>【FOR SQLSTATE ‘23000’】>【FOR SQLEXCEPTION 】

6.异常回滚或继续执行
CREATE DEFINER=root@% PROCEDURE insert_article_tags_3(IN article_id INT, IN tag_id INT)

BEGIN

    DECLARE has_error int(11);
		
    DECLARE EXIT HANDLER FOR SQLEXCEPTION
		BEGIN
		ROLLBACK;
		SELECT 'An error has occurred, operation rollbacked and the stored procedure was terminated' as  errmsg;
		END;
 
    /*DECLARE EXIT HANDLER FOR SQLSTATE '23000'
    SELECT 'SQLSTATE 23000 invoked' as  errmsg;*/

    -- insert a new record into article_tags
    INSERT INTO article_tags(article_id,tag_id)
    VALUES(article_id,tag_id);

    -- return tag count for the article
    SELECT COUNT(*) FROM article_tags;
END

7.异常条件判断

CREATE DEFINER=`root`@`%` PROCEDURE `insert_article_tags_5`(IN article_id INT, IN tag_id INT)
BEGIN

    DECLARE has_error int(11);
		
    DECLARE EXIT HANDLER FOR SQLEXCEPTION
		BEGIN
		ROLLBACK;
		SELECT 'An error has occurred, operation rollbacked and the stored procedure was terminated' as  errmsg;
		END;

    DECLARE CONTINUE	HANDLER FOR 1062 SET has_error = 5;
        SELECT 'MySQL error code 1062 invoked' as  errmsg;

    
		
    /*DECLARE EXIT HANDLER FOR SQLSTATE '23000'
    SELECT 'SQLSTATE 23000 invoked' as  errmsg;*/

    -- insert a new record into article_tags
    INSERT INTO article_tags(article_id,tag_id)
    VALUES(article_id,tag_id);

    -- return tag count for the article
    SELECT COUNT(*) FROM article_tags;
		
		IF has_error <> 5 THEN 
		  SELECT CONCAT('ERR0R ', has_error) as  msg; 
		ELSE
		  SELECT CONCAT('正常 ', has_error) as  msg; 
		END IF;
END

运行结果：

CALL insert_article_tags_5(1,3);
 Result1: MySQL error code 1062 invoked
 Result2: 4
 Result3: ERR0R 5

注意：别把异常判断放在了出现异常的前面，如存储过程insert_article_tags_4就是错误的，这样就找不到has_error值了

8.游标示例

CREATE TABLE `t_users`
   (
  `ID` BIGINT(20) UNSIGNED NOT NULL AUTO_INCREMENT,
  `user_name` VARCHAR(60),
  `user_pass` VARCHAR(64),
   PRIMARY KEY (`ID`)
 );
 

  INSERT INTO t_users VALUES(null,'sheng','sheng123'),
  (null,'yu','yu123'),
 (null,'ling','ling123'); 
 
DELIMITER //
DROP PROCEDURE test_cursor ;
CREATE PROCEDURE test_cursor (out result varchar(100))
BEGIN
DECLARE name VARCHAR(20);
DECLARE pass VARCHAR(20);
DECLARE done INT;
DECLARE cur_test CURSOR FOR SELECT user_name,user_pass FROM t_users;
DECLARE continue handler FOR SQLSTATE '02000' SET done = 1;
OPEN cur_test;
repeat
FETCH cur_test into name,pass;
SELECT concat(',',name,pass);
until done
END repeat;
CLOSE cur_test;
END //

call test_cursor(@test)
select @test