MySQL Database Administration – Part1
Running and Shutting down MySQL Server:
First check if your MySQL server is running or not. You can use the following command to check this:
ps -ef | grep mysqld
If your MySql is running, then you will see mysqld process listed out in your result. If server is not running, then you can start it by using the following command:
root@DB# cd /usr/bin
./safe_mysqld
Now, if you want to shut down an already running MySQL server, then you can do it by using the following command:
root@DB# cd /usr/bin
./mysqladmin -u root -p shutdown
Enter password: ******
Setting Up a MySQL User Account:
For adding a new user to MySQL, you just need to add a new entry to user table in database mysql.
Below is an example of adding new user satya with SELECT, INSERT and UPDATE privileges with the password satyatest ; the SQL query would be:
root@DB# mysql -u root -p
Enter password:*******
mysql> use mysql;
Database changed
mysql> INSERT INTO user
(host, user, password,
select_priv, insert_priv, update_priv)
VALUES (‘localhost’, ‘satya’,
PASSWORD(‘satyatest’), ‘Y’, ‘Y’, ‘Y’);
Query OK, 1 row affected (0.20 sec)
mysql> FLUSH PRIVILEGES;
Query OK, 1 row affected (0.01 sec)
mysql> SELECT host, user, password FROM user WHERE user = ‘satya’;
+———–+———+——————+
| host | user | password |
+———–+———+——————+
| localhost | satya | 6f8c114b58f2ce9e |
+———–+———+——————+
1 row in set (0.00 sec)
When adding a new user, remember to encrypt the new password using PASSWORD() function provided by MySQL. As you can see in the above example the password satyatest is encrypted to 6f8c114b58f2ce9e.
Notice the FLUSH PRIVILEGES statement. This tells the server to reload the grant tables. If you don’t use it, then you won’t be able to connect to mysql using the new user account at least until the server is rebooted.
You can also specify other privileges to a new user by setting the values of following columns in user table to ‘Y’ when executing the INSERT query or you can update them later using UPDATE query.
Select_priv
Insert_priv
Update_priv
Delete_priv
Create_priv
Drop_priv
Reload_priv
Shutdown_priv
Process_priv
File_priv
Grant_priv
References_priv
Index_priv
Alter_priv
Another way of adding user account is by using GRANT SQL command; following example will add user swapnil with password swapniltest for a particular database called CRM.
root@DB# mysql -u root -p password;
Enter password:*******
mysql> use mysql;
Database changed
mysql> GRANT SELECT,INSERT,UPDATE,DELETE,CREATE,DROP
-> ON CRM.*
-> TO ‘swapnil’@’localhost’
-> IDENTIFIED BY ‘swapniltest’;
This will also create an entry in mysql database table called user.
NOTE: MySQL does not terminate a command until you give a semi colon (;) at the end of SQL command.
The /etc/my.cnf File Configuration:
Most of the cases, you should not touch this file. By default, it will have the following entries:
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
[mysql.server]
user=mysql
basedir=/var/lib
[safe_mysqld]
err-log=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
Here, you can specify a different directory for error log, otherwise you should not change any entry in this table.
Administrative MySQL Command:
Here is the list of important MySQL commands, which you will use time to time to work with MySQL database:
USE Databasename : This will be used to select a particular database in MySQL work area.
SHOW DATABASES: Lists the databases that are accessible by the MySQL DBMS.
SHOW TABLES: Shows the tables in the database once a database has been selected with the use command.
SHOW COLUMNS FROM tablename: Shows the attributes, types of attributes, key information, whether NULL is permitted, defaults, and other information for a table.
SHOW INDEX FROM tablename: Presents the details of all indexes on the table, including the PRIMARY KEY.
SHOW TABLE STATUS LIKE tablename\G: Reports details of the MySQL DBMS performance and statistics.
Installing MySQL on Linux/UNIX
The recommended way to install MySQL on a Linux system is via RPM. MySQL have the following RPMs available for download on its web site:
MySQL – The MySQL database server, which manages databases and tables, controls user access, and processes SQL queries.
MySQL-client – MySQL client programs, which make it possible to connect to and interact with the server.
MySQL-devel – Libraries and header files that come in handy when compiling other programs that use MySQL.
MySQL-shared – Shared libraries for the MySQL client.
MySQL-bench – Benchmark and performance testing tools for the MySQL database server.
The MySQL RPMs listed here are all built on a SuSE Linux system, but they’ll usually work on other Linux variants with no difficulty.
Now, follow the following steps to proceed for installation:
Login to the system using root user.
Switch to the directory containing the RPMs:
Install the MySQL database server by executing the following command. Remember to replace the filename in italics with the file name of your RPM.
[root@DB]# rpm -i MySQL-5.0.9-0.i386.rpm
Above command takes care of installing MySQL server, creating a user of MySQL, creating necessary configuration and starting MySQL server automatically.
You can find all the MySQL related binaries in /usr/bin and /usr/sbin. All the tables and databases will be created in /var/lib/mysql directory.
This is optional but recommended step to install the remaining RPMs in the same manner:
[root@DB]# rpm -i MySQL-client-5.0.9-0.i386.rpm
[root@DB]# rpm -i MySQL-devel-5.0.9-0.i386.rpm
[root@DB]# rpm -i MySQL-shared-5.0.9-0.i386.rpm
[root@DB]# rpm -i MySQL-bench-5.0.9-0.i386.rpm
Installing MySQL on Windows:
Default installation on any version of Windows is now much easier than it used to be, as MySQL now comes neatly packaged with an installer. Simply download the installer package, unzip it anywhere, and run setup.exe.
Default installer setup.exe will walk you through the trivial process and by default will install everything under C:\mysql.
Test the server by firing it up from the command prompt the first time. Go to the location of the mysqld server which is probably C:\mysql\bin, and type:
mysqld.exe –console
NOTE: If you are on NT, then you will have to use mysqld-nt.exe instead of mysqld.exe
If all went well, you will see some messages about startup and InnoDB. If not, you may have a permissions issue. Make sure that the directory that holds your data is accessible to whatever user (probably mysql) the database processes run under.
MySQL will not add itself to the start menu, and there is no particularly nice GUI way to stop the server either. Therefore, if you tend to start the server by double clicking the mysqld executable, you should remember to halt the process by hand by using mysqladmin, Task List, Task Manager, or other Windows-specific means.
Verifying MySQL Installation:
After MySQL has been successfully installed, the base tables have been initialized, and the server has been started, you can verify that all is working as it should via some simple tests.
Use the mysqladmin Utility to Obtain Server Status:
Use mysqladmin binary to check server version. This binary would be available in /usr/bin on linux and in C:\mysql\bin on windows.
[root@DB]# mysqladmin –version
It will produce the following result on Linux. It may vary depending on your installation:
mysqladmin Ver 8.23 Distrib 5.0.9-0, for redhat-linux-gnu on i386
If you do not get such message, then there may be some problem in your installation and you would need some help to fix it.
Execute simple SQL commands using MySQL Client:
You can connect to your MySQL server by using MySQL client using mysql command. At this moment, you do not need to give any password as by default it will be set to blank.
So just use following command
[root@DB]# mysql
It should be rewarded with a mysql> prompt. Now, you are connected to the MySQL server and you can execute all the SQL command at mysql> prompt as follows:
mysql> SHOW DATABASES;
+———-+
| Database |
+———-+
| mysql |
| test |
+———-+
2 rows in set (0.13 sec)
Post-installation Steps:
MySQL ships with a blank password for the root MySQL user. As soon as you have successfully installed the database and client, you need to set a root password as follows:
[root@DB]# mysqladmin -u root password “new_password”;
Now to make a connection to your MySQL server, you would have to use the following command:
[root@DB]# mysql -u root -p
Enter password:*******
UNIX users will also want to put your MySQL directory in your PATH, so you won’t have to keep typing out the full path every time you want to use the command-line client. For bash, it would be something like:
export PATH=$PATH:/usr/bin:/usr/sbin
Running MySQL at boot time:
If you want to run MySQL server at boot time, then make sure you have following entry in /etc/rc.local file.
/etc/init.d/mysqld start
Also,you should have mysqld binary in /etc/init.d/ directory.
