MySQL异常处理浅析

MySQL的异常处理分析如下：

标准格式

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DECLARE handler_type HANDLER FOR condition_value[,...] statementhandler_type:  CONTINUE | EXIT | UNDO --这个暂时不支持condition_value:  SQLSTATE [VALUE] sqlstate_value | condition_name | SQLWARNING | NOT FOUND | SQLEXCEPTION | mysql_error_codecondition_value细节

1、常用MYSQL ERROR CODE 列表

http://dev.mysql.com/doc/refman/5.0/en/error-messages-server.html
更多错误列表见MySQL安装路径下
比如我的/usr/local/mysql/share/mysql/errmsg.txt
说明一下：SQLSTATE [VALUE] sqlstate_value这种格式是专门为ANSI SQL 和 ODBC以及其他的标准.
并不是所有的MySQL ERROR CODE 都映射到SQLSTATE。

2、如果你不想插ERROR CODE的话，就用速记条件来代替

SQLWARNING 代表所有以01开头的错误代码
NOT FOUND 代表所有以02开头的错误代码，当然也可以代表一个游标到达数据集的末尾。
SQLEXCEPTION 代表除了SQLWARNING和NOT FOUND 的所有错误代码

3、我们现在就用手册上的例子

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CREATE TABLE t (s1 int,primary key (s1));mysql> use t_girlDatabase changedmysql> CREATE TABLE t (s1 int,primary key (s1));Query OK, 0 rows affected (0.00 sec)mysql> mysql> mysql> DELIMITER ||mysql> CREATE PROCEDURE handlerdemo ()  -> BEGIN  -> DECLARE EXIT HANDLER FOR SQLSTATE '23000' BEGIN END; -- 遇到重复键值就退出  -> SET @x = 1;  -> INSERT INTO t VALUES (1);  -> SET @x = 2;  -> INSERT INTO t VALUES (1);  -> SET @x = 3;  -> END||Query OK, 0 rows affected (0.00 sec)mysql> DELIMITER ;mysql> call handlerdemo();Query OK, 0 rows affected (0.00 sec)mysql> select @x;+------+| @x |+------+| 2 | +------+1 row in set (0.00 sec)mysql> call handlerdemo();Query OK, 0 rows affected (0.00 sec)mysql> select @x;+------+| @x |+------+| 1 | +------+1 row in set (0.00 sec)mysql>

现在来看一下遇到错误继续的情况

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mysql> truncate table t;Query OK, 0 rows affected (0.01 sec)mysql> DELIMITER $$mysql> DROP PROCEDURE IF EXISTS `t_girl`.`handlerdemo`$$Query OK, 0 rows affected (0.00 sec)mysql> CREATE DEFINER=`root`@`localhost` PROCEDURE `handlerdemo`()  -> BEGIN  -> DECLARE CONTINUE HANDLER FOR SQLSTATE '23000' BEGIN END;  -> SET @x = 1;  -> INSERT INTO t VALUES (1);  -> SET @x = 2;  -> INSERT INTO t VALUES (1);  -> SET @x = 3;  -> END$$Query OK, 0 rows affected (0.01 sec)mysql> DELIMITER ;mysql> call handlerdemo();Query OK, 0 rows affected (0.00 sec)mysql> select @x;+------+| @x |+------+| 3 | +------+1 row in set (0.00 sec)mysql> call handlerdemo();Query OK, 0 rows affected (0.00 sec)mysql> select @x;+------+| @x |+------+| 3 | +------+1 row in set (0.00 sec)mysql>

可以看到，始终执行到最后。
当然，上面的SQLSTATE '23000'可以替换为1062
我们来看一下警告。

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mysql> alter table t add s2 int not null;Query OK, 0 rows affected (0.01 sec)Records: 0 Duplicates: 0 Warnings: 0

此列没有默认值，插入的时候会出现警告或者1364错误提示。

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mysql> DELIMITER $$mysql> DROP PROCEDURE IF EXISTS `t_girl`.`handlerdemo`$$Query OK, 0 rows affected, 1 warning (0.00 sec)mysql> CREATE DEFINER=`root`@`localhost` PROCEDURE `handlerdemo`()  -> BEGIN  -> DECLARE CONTINUE HANDLER FOR 1062 BEGIN END;  -> DECLARE CONTINUE HANDLER FOR SQLWARNING  -> BEGIN  -> update t set s2 = 2;  -> END;  -> DECLARE CONTINUE HANDLER FOR 1364  -> BEGIN  -> INSERT INTO t(s1,s2) VALUES (1,3);  -> END;   -> SET @x = 1;  -> INSERT INTO t(s1) VALUES (1);  -> SET @x = 2;  -> INSERT INTO t(s1) VALUES (1);  -> SET @x = 3;  -> END$$Query OK, 0 rows affected (0.00 sec)mysql> DELIMITER ;mysql> call handlerdemo();Query OK, 0 rows affected (0.00 sec)mysql> select * from t;+----+----+| s1 | s2 |+----+----+| 1 | 3 | +----+----+1 row in set (0.00 sec)

遇到错误的时候插入的新记录。

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mysql> select @x;+------+| @x |+------+| 3 | +------+1 row in set (0.00 sec)