Linux Ask! is a Q & A web site specific for Linux related questions. Questions are collected, answered and audited by experienced Linux users.
How to create a new MySQL user?
Answer:
1. Enter the MySQL shell using root account
mysql -u root -p mysql
2. Execute the SQL like the followings
GRANT ALL PRIVILEGES ON db1.* TO 'user1'@'localhost' IDENTIFIED BY 'password' WITH GRANT OPTION;
FLUSH PRIVILEGES;
3. Now try to login using user1 account
mysql -u user1 -p db1
MySQL binary log files take all of my disk space
Answer:
If you have enabled binary log in your MySQL server, most likely you are using the replication feature. You don't need to keep the binary log forever, so in the my.cnf, add the line
expire_logs_days = 10
So your MySQL server (master) would keep at most binary log for 10 days. (Notes: you might need to adjust this value, make sure your MySQL slave is able to catch up the updates within 10 days)
However, if you are not using replication, you can consider disable the binary log, e.g. edit the my.cnf, comment out the "log-bin"
# log-bin
How to pretty print my.cnf with a one-liner?
Answer:
A very cool command.
perl -ne 'm/^([^#][^\s=]+)\s*(=.*|)/ && printf("%-35s%s\n", $1, $2)' /etc/my.cnf
Reference: http://www.mysqlperformanceblog.com/2009/06/15/how-to-pretty-print-mycnf-with-a-one-liner/
How to avoid SQL injection in PHP?
Answer:
The easiest method is to use the mysql_real_escape_string function
Example:
$query = sprintf("SELECT * FROM users WHERE user='%s' AND password='%s'",
mysql_real_escape_string($user),
mysql_real_escape_string($password));
Reference: http://php.net/manual/en/function.mysql-real-escape-string.php
How to rename table in MySQL
Answer:
Login into MySQL shell, and enter the following SQL
mysql> USE my_db;
mysql> RENAME TABLE old_table TO new_table;
Query OK, 0 rows affected (0.00 sec)
That's all what you need.
