MYSQL必讀
# mysql --help|grep dummy  
 -U, --i-am-a-dummy Synonym for option --safe-updates, -U. 
i-am-a-dummy  FALSE

MYSQL必讀
# mysql -uroot -poldboy123 -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

MYSQL必讀
# alias mysql='mysql -U' 
# 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 
# echo "alias mysql='mysql -U'" >>/etc/profile 
# . /etc/profile 
# tail -1 /etc/profile 
alias mysql='mysql -U'