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今天，一位原公司的同事，打电话来问我说误操作了数据库数据，如何恢复。他原本的想法是登录数据库update一个记录，结果忘了加where，于是悲剧发生了。今天，我们不讲如何恢复误操作的数据，我们讲讲如何从源头上避免这样的问题，这才是避免类似问题的根本措施。好了。我们直接进入主题：

1、MySQL帮助说明

[root@liuyazhuang151 ~]# mysql --help|grep dummy      
 -U, --i-am-a-dummy Synonym for option --safe-updates, -U.
i-am-a-dummy      FALSE

在mysql命令加上选项-U后，当发出没有WHERE或LIMIT关键字的UPDATE或DELETE时，mysql程序就会拒绝执行

2、指定-U登录测试


[root@liuyazhuang151 ~]# mysql -uroot -proot -S /data/3306/mysql.sock -U
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 14
Server version: 5.5.32-log MySQL Community Server (GPL)
Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> delete from oldboy.student;
ERROR 1175 (HY000): You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column
mysql> quit
Bye

提示：不加条件无法删除，目的达到。


3、做成别名防止他人和DBA误操作


[root@liuyazhuang151 ~]# alias mysql='mysql -U'
[root@liuyazhuang151 ~]# mysql -uroot -poldboy123 -S /data/3306/mysql.sock
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 15
Server version: 5.5.32-log MySQL Community Server (GPL)
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> delete from oldboy.student;
ERROR 1175 (HY000): You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column
mysql> delete from oldboy.student where Sno=5;
Query OK, 1 row affected (0.02 sec)
mysql> quit
Bye
[root@liuyazhuang151 ~]# echo "alias mysql='mysql -U'" >>/etc/profile
[root@liuyazhuang151 ~]# . /etc/profile
[root@liuyazhuang151 ~]# tail -1 /etc/profile
alias mysql='mysql -U'

4、结论：

在mysql命令加上选项-U后，当发出没有WHERE或LIMIT关键字的UPDATE或DELETE时，mysql程序拒绝执行