Installing MYSQL

How to installing MySQL server on CentOS 5 x64 -

1. Login as root user to server.

2. Execute following commands from shell:

# yum install mysql mysql-server mysql-devel
This command will check system configuration and calculates the dependencies required to run Mysql. It will display the list of packages need to be installed and in the end:
……
Total download size: 35 M
is this ok [y/N]: y
Press ‘y’ like above. This will install mysql server and mysql client on your machine.

3. Now mysql is installed on your server. Now if you execute the following command to connect to mysql 

# mysql

And error message like this below is printed:

ERROR 2002 (HY000): Can’t connect to local MySQL server through socket ‘/var/lib/mysql/mysql.sock’ (2)
Then it means mysql is not running. You need to start the mysql service first. So execute following command:
# /etc/init.d/mysqld start
It will print the following message:
Starting MySQL:                                            [  OK  ]
It means everything is fine. Mysql is up and running and ready to connect on default port 3306.

4. Now you can connect to mysql from shell prompt. Execute following command:

# mysql

You might get this error message:
ERROR 1045 (28000): Access denied for user ‘root’@'localhost’ (using password: NO)
Now you might think that you have not provided password that is why above error message. So you try again using -p option like this

# mysql -u root -p
Enter password:

ERROR 1045 (28000): Access denied for user ‘root’@'localhost’ (using password: NO)
Oops error message again. The Mysql is installed with blank password, so you must be wondering what went wrong. But you need to check with which user name mysql has been installed. (In my case MySQL is installed with default user ‘mysql’).

You need to check ‘/etc/my.cnf’ file and check following ‘user’ property in ‘mysqld’ section:
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
user=mysql
So like above ‘mysql’ is default user with blank password. Now you can connect as follow (As password is blank so hit enter when asked to enter password.):

# mysql -u mysql -p
Enter password:

Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 4
Server version: 5.0.77 Source distribution
Type ‘help;’ or ‘\h’ for help. Type ‘\c’ to clear the buffer.
mysql>

5. OK. Good going till now. When you try to execute “use mysql;” command and if you get error message like this -

ERROR 1045 (28000): Access denied for user ”@’localhost’ (using password: NO)
Then you must be wondering what the hell happened. I mean even If not root then atleast mysql user should have been able to execute all the SQL statements like - create database, alter database, or even a simple use or select statement, but it is not happening. Somehow it seems that mysql user has no priviledges. Now follow below points. Come out of the mysql prompt using quit command or Ctrl+C

6. Stop mysql server by executing following command:

# /etc/init.d/mysqld stop.

Once you get the success message go to step 7.

7. Start MySQL in safe with skipping grant tables that stores the password. Execute following command:

# mysqld_safe –skip-grant-tables

8. Now connect to mysql server as root user :

# mysql –user=root

9. Now change the password by executing following commands and then exit:

# mysql > update user set Password=PASSWORD(’new-password’) where user=’root’;

# mysql > flush privileges;

# mysql > exit;

Here new-password should have value which you want to have for root user while connecting to MySQL server.

10. Now Reconnect to mysql-server using ‘new-password’ you set in step 9:

# mysql -u mysql -p
Enter password:

Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 4
Server version: 5.0.77 Source distribution
Type ‘help;’ or ‘\h’ for help. Type ‘\c’ to clear the buffer.
mysql>

Now you are connected to mysql with root privileges.