업데이트 전 구문으로 해시를 생성하는 트리거

Question

업데이트 후 생성되는 해시를 얻으려면 어떻게해야합니까?

thufir@dur:~$ 
thufir@dur:~$ mysql -u root -p 
Enter password: 
Welcome to the MySQL monitor. Commands end with ; or \g. 
Your MySQL connection id is 138 
Server version: 5.1.58-1ubuntu1 (Ubuntu) 

Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved. 
This software comes with ABSOLUTELY NO WARRANTY. This is free software, 
and you are welcome to modify and redistribute it under the GPL v2 license 

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. 

mysql> use nntp; 
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 
mysql> show tables; 
+---------------------+ 
| Tables_in_nntp  | 
+---------------------+ 
| articles   | 
| newsgroups   | 
| newsgroups_articles | 
+---------------------+ 
3 rows in set (0.00 sec) 

mysql> describe newsgroups; 
+-----------+----------+------+-----+---------+----------------+ 
| Field  | Type  | Null | Key | Default | Extra   | 
+-----------+----------+------+-----+---------+----------------+ 
| id  | int(11) | NO | PRI | NULL | auto_increment | 
| newsgroup | longtext | NO |  | NULL |    | 
| hash  | char(32) | NO |  | NULL |    | 
+-----------+----------+------+-----+---------+----------------+ 
3 rows in set (0.00 sec) 

mysql> show triggers; 
+-----------+--------+------------+-----------------------------------------------------+--------+---------+----------+----------------+----------------------+----------------------+--------------------+ 
| Trigger | Event | Table  | Statement           | Timing | Created | sql_mode | Definer  | character_set_client | collation_connection | Database Collation | 
+-----------+--------+------------+-----------------------------------------------------+--------+---------+----------+----------------+----------------------+----------------------+--------------------+ 
| make_hash | INSERT | newsgroups | BEGIN 
    set new.hash = md5(new.newsgroup); 
    END | BEFORE | NULL |   | root@localhost | utf8     | utf8_general_ci  | latin1_swedish_ci | 
+-----------+--------+------------+-----------------------------------------------------+--------+---------+----------+----------------+----------------------+----------------------+--------------------+ 
1 row in set (0.00 sec) 

mysql> 
mysql> 
mysql> DELIMITER $$ 
mysql> 
mysql> USE `nntp`$$ 
Database changed 
mysql> CREATE 
    -> TRIGGER `nntp`.`make_hash_update` 
    -> AFTER UPDATE ON `nntp`.`newsgroups` 
    -> FOR EACH ROW 
    -> BEGIN 
    -> set old.hash = md5(new.newsgroup); 
    -> END$$ 
ERROR 1362 (HY000): Updating of OLD row is not allowed in trigger 
mysql> 
mysql> quit; 
    -> exit 
    -> ^CCtrl-C -- exit! 
Aborted 
thufir@dur:~$ 

또한, 워크 벤치에서, 나는 이전 트리거 참조 :

을 수 있지만 추가적인 트리거를 추가하는 방법을 볼 수 없습니다.

Answer 1

업데이트 이후, 업데이트 전이고 새로운 것입니다. 구문을 이해하지는 못 하겠지만 적어도 구문 오류를 생성하지는 않습니다. 워크 벤치를 사용하고 싶습니다.

thufir@dur:~$ 
thufir@dur:~$ mysql -u root -p 
Enter password: 
Welcome to the MySQL monitor. Commands end with ; or \g. 
Your MySQL connection id is 144 
Server version: 5.1.58-1ubuntu1 (Ubuntu) 

Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved. 
This software comes with ABSOLUTELY NO WARRANTY. This is free software, 
and you are welcome to modify and redistribute it under the GPL v2 license 

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement. 

mysql> use nntp; 
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 
mysql> show triggers; 
+-----------+--------+------------+-----------------------------------------------------+--------+---------+----------+----------------+----------------------+----------------------+--------------------+ 
| Trigger | Event | Table  | Statement           | Timing | Created | sql_mode | Definer  | character_set_client | collation_connection | Database Collation | 
+-----------+--------+------------+-----------------------------------------------------+--------+---------+----------+----------------+----------------------+----------------------+--------------------+ 
| make_hash | INSERT | newsgroups | BEGIN 
    set new.hash = md5(new.newsgroup); 
    END | BEFORE | NULL |   | root@localhost | utf8     | utf8_general_ci  | latin1_swedish_ci | 
+-----------+--------+------------+-----------------------------------------------------+--------+---------+----------+----------------+----------------------+----------------------+--------------------+ 
1 row in set (0.00 sec) 

mysql> show create trigger make_hash; 
+-----------+----------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------+----------------------+--------------------+ 
| Trigger | sql_mode | SQL Original Statement                                    | character_set_client | collation_connection | Database Collation | 
+-----------+----------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------+----------------------+--------------------+ 
| make_hash |   | CREATE DEFINER=`root`@`localhost` TRIGGER `nntp`.`make_hash` 
BEFORE INSERT ON `nntp`.`newsgroups` 
FOR EACH ROW 
BEGIN 
    set new.hash = md5(new.newsgroup); 
    END | utf8     | utf8_general_ci  | latin1_swedish_ci | 
+-----------+----------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------------------+----------------------+--------------------+ 
1 row in set (0.00 sec) 

mysql> 
mysql> DELIMITER $$ 
mysql> 
mysql> USE `nntp`$$ 
Database changed 
mysql> CREATE 
    -> TRIGGER `nntp`.`make_hash_update` 
    -> BEFORE UPDATE ON `nntp`.`newsgroups` 
    -> FOR EACH ROW 
    -> BEGIN 
    -> set new.hash = md5(new.newsgroup); 
    -> END$$ 
Query OK, 0 rows affected (0.19 sec) 

mysql> 
mysql> show triggers; 
    -> ^CCtrl-C -- exit! 
Aborted 
thufir@dur:~$