作者：杨涛涛
背景
今天的文章来源于今天客户问的一个问题。
问题大概意思是：我正在从 Oracle 迁移到 MySQL，数据已经转换为单纯的 INSERT 语句。由于语句很多，每次导入的时候不知道怎么定位到错误的语句。 如果 INSERT 语句少也就罢了，我可以手工看，不过 INSERT 语句很多，我怎么定位到是哪些语句出错了，我好改正呢？总不能每次遇到的错误的时候改一下，在重新运行继续改正吧？有没有简单点的方法。
其实 MySQL 自身就有错误诊断区域，如果能好好利用，则事半功倍。下面我来简单说下怎么使用错误诊断区域。
比如说我要插入的表结构为 n3, 保存错误信息的日志表为 error_log 两个表结构如下：
mysql
-- tables definition.
[ytt]>create table n3 (id int not null, id2 int generated always as ((mod(id,10))));
Query OK, 0 rows affected (0.04 sec)
[ytt]>create table error_log (sqltext text, error_no int unsigned, error_message text);
Query OK, 0 rows affected (0.04 sec)
假设插入的语句，为了演示，我这里仅仅简单写了 8 条语句。
mysql
-- statements body.
set @a1 = "INSERT INTO n3 (id) VALUES(100)";
set @a2 = "INSERT INTO n3 (id) VALUES('test')";
set @a3 = "INSERT INTO n3 (id) VALUES('test123')";
set @a4 = "INSERT INTO n3 (id) VALUES('123test')";
set @a5 = "INSERT INTO n3 (id) VALUES(200)";
set @a6 = "INSERT INTO n3 (id) VALUES(500)";
set @a7 = "INSERT INTO n3 (id) VALUES(null)";
set @a8 = "INSERT INTO n3 (id) VALUES(10000000000000)";
MySQL 的错误代码很多，不过总体归为三类：
- sqlwarning SQLSTATE 代码开始为 '01'
- not found SQLSTATE 代码开始为 '02'
- sqlexception SQLSTATE 代码开始非 '00','01','02' 的所有错误代码。
为了简单方便，我们写这些代码到存储过程里。以下为示例存储过程。
mysql
-- stored routines body.
drop procedure if exists sp_insert_simple;
delimiter ||
create procedure sp_insert_simple()
l1:begin
DECLARE i,j TINYINT DEFAULT 1; -- loop counter.
DECLARE v_errcount,v_errno INT DEFAULT 0; -- error count and error number.
DECLARE v_msg TEXT; -- error details.
declare v_sql json; -- store statements list.
declare v_sql_keys varchar(100); -- array index.
declare v_sql_length int unsigned; -- array length.
-- Handler declare.
DECLARE CONTINUE HANDLER FOR SQLEXCEPTION,SQLWARNING,NOT FOUND -- exception in mysql routines.
l2:BEGIN
get stacked diagnostics v_errcount = number;
set j = 1;
WHILE j <= v_errcount
do
GET stacked DIAGNOSTICS CONDITION j v_errno = MYSQL_ERRNO, v_msg = MESSAGE_TEXT;
-- record error messages into table.
INSERT INTO error_log(sqltext,error_no,error_message) VALUES (@sqltext, v_errno,v_msg);
SET j = j + 1;
END WHILE;
end;
-- sample statements array.
set v_sql = '{
"a1": "INSERT INTO n3 (id) VALUES(100)",
"a2": "INSERT INTO n3 (id) VALUES(''test'')",
"a3": "INSERT INTO n3 (id) VALUES(''test123'')",
"a4": "INSERT INTO n3 (id) VALUES(''123test'')",
"a5": "INSERT INTO n3 (id) VALUES(200)",
"a6": "INSERT INTO n3 (id) VALUES(500)",
"a7": "INSERT INTO n3 (id) VALUES(null)",
"a8": "INSERT INTO n3 (id) VALUES(10000000000000)"
}';
set i = 1;
set v_sql_length = json_length(v_sql);
while i <=v_sql_length do
set v_sql_keys = concat('$.a',i);
set @sqltext = replace(json_extract(v_sql,v_sql_keys),'"','');
prepare s1 from @sqltext;
execute s1;
set i = i + 1;
end while;
drop prepare s1;
-- invoke procedure.
-- call sp_insert_simple;
end;
||
delimiter ;
我们来调用这个存储过程看下结果。
mysql
[(none)]>use ytt
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
Database changed
[ytt]>call sp_insert_simple;
Query OK, 0 rows affected (0.05 sec)
表N3的结果。
mysql
[ytt]>select * from n3;
+-----+------+
| id | id2 |
+-----+------+
| 100 | 0 |
| 200 | 0 |
| 500 | 0 |
+-----+------+
3 rows in set (0.00 sec)
错误日志记录了所有错误的语句。
mysql
[ytt]>select * from error_log;
+--------------------------------------------+----------+-------------------------------------------------------------+
| sqltext | error_no | error_message |
+--------------------------------------------+----------+-------------------------------------------------------------+
| INSERT INTO n3 (id) VALUES('test') | 1366 | Incorrect integer value: 'test' for column 'id' at row 1 |
| INSERT INTO n3 (id) VALUES('test123') | 1366 | Incorrect integer value: 'test123' for column 'id' at row 1 |
| INSERT INTO n3 (id) VALUES('123test') | 1265 | Data truncated for column 'id' at row 1 |
| INSERT INTO n3 (id) VALUES(null) | 1048 | Column 'id' cannot be null |
| INSERT INTO n3 (id) VALUES(10000000000000) | 1264 | Out of range value for column 'id' at row 1 |
+--------------------------------------------+----------+-------------------------------------------------------------+
5 rows in set (0.00 sec)
其实这个问题如果用 Python 或 PHP 等外部语言来说，将会更简单，思路差不多。