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 程式師世界 >> 數據庫知識 >> MYSQL數據庫 >> MySQL綜合教程 >> MySQL完成差集(Minus)和交集(Intersect)測試申報

MySQL完成差集(Minus)和交集(Intersect)測試申報

編輯:MySQL綜合教程

MySQL完成差集(Minus)和交集(Intersect)測試申報。本站提示廣大學習愛好者:(MySQL完成差集(Minus)和交集(Intersect)測試申報)文章只能為提供參考,不一定能成為您想要的結果。以下是MySQL完成差集(Minus)和交集(Intersect)測試申報正文


有很多開辟人員在操作MySQL數據庫的時刻都碰到過誤操作的情形,例如更新數據庫的時刻update語句忘卻加上where前提,就會形成極其喜劇的成果。本文就針對避免MySQL數據庫誤操作的辦法做出以下詳解:

1、mysql贊助解釋

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

在mysql敕令加上選項-U後,當收回沒有WHERE或LIMIT症結字的UPDATE或DELETE時,mysql法式就會謝絕履行

2、指定-U登錄測試

# 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

提醒:此處不加前提沒法刪除,目標到達。

3、做成別號避免DBA誤操作

# 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'

結論:在mysql敕令加上選項-U後,當收回沒有WHERE或LIMIT症結字的UPDATE或DELETE時,mysql法式謝絕履行

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