Linux Ask! is a Q & A web site specific for Linux related questions. Questions are collected, answered and audited by experienced Linux users.
Can't connect to local MySQL server through socket
Answer:
Sometimes when you type the mysql command, it shows:
Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2)
The cause of this problem is the MySQL socket file is not in the default location, e.g. /tmp/mysql.sock
To fix, edit the MySQL configurations, e.g. /etc/my.cnf, add the following lines
[client]
socket=/tmp/mysql.sock
Replace string in MySQL
Answer:
Replace a string with the UPDATE statement is easy in MySQL
E.g.
mysql> UPDATE table1 SET name = REPLACE (name, 'foo', 'bar');
Set the auto increment start value in MySQL?
Answer:
In MySQL, you can change the table's auto increment start value by the following command.
mysql> ALTER TABLE `my_table` AUTO_INCREMENT = 2000;
Query OK, 2 rows affected (0.06 sec)
Records: 2 Duplicates: 0 Warnings: 0
Block a client from connecting to MySQL if too many errors
Answer:
You can block a client from connecting to MySQL if they introduced too many errors, e.g. sending incorrect password for authentication, insufficient privileges when connecting to a database etc.
To set the number of maximum allowed error, edit the MySQL configurations, e.g. /etc/my.cnf
..
max_connect_errors=100
..So if a client exceeded this value, they will be blocked from connecting to the server.
Don't forget to restart MySQL to take effect.
# /sbin/service mysqld restart
Set the maximum allowed number of connections in MySQL
Answer:
MySQL has a setting which prevent the database from overloaded due to too many concurrent connections. This value should depends on the processing power of your database server, e.g. CPU, memory, disks I/O.
To change the value, edit the MySQL configurations, e.g. /etc/my.cnf
..
max_connections=100
..So if a client connecting to the database exceeded this value, they will be blocked.
Don't forget to restart MySQL to take effect.
# /sbin/service mysqld restart
