Working with mysql database on CentOS

1. Login in root mode

mysql -u root -p

enter your root password (the root password of mysql is separated with system account).

2. Listing databases 

show databases

3. Select a database to backup

a. Without compress backup

Syntax: mysqldump --opt -u [uname] -p[pass] [dbname] > [backupfile.sql]

mysqldump --opt -u root -p renaisz7_renaissancedb > renaisz7_renaissancedb.sql

Or

Syntax: mysqldump -u root -p renaisz7_renaissancedb > renaisz7_renaissancedb.sql

--opt parameter : password will be prompted to the sql file, when decompressing the sql file it will be required.

With mysqldump command you can specify certain tables of your database you want to backup. For example, to back up only php_tutorials and asp_tutorials tables from the 'Tutorials' database accomplish the command below. Each table name has to be separated by space.

mysqldump -u root -p Tutorials php_tutorials asp_tutorials > tut_backup.sql

Sometimes it is necessary to back up more that one database at once. In this case you can use the --database option followed by the list of databases you would like to backup. Each database name has to be separated by space.

mysqldump -u root -p --databases Tutorials Articles Comments > content_backup.sql

If you want to back up all the databases in the server at one time you should use the --all-databases option. It tells MySQL to dump all the databases it has in storage.

mysqldump -u root -p --all-databases > alldb_backup.sql

The mysqldump command has also some other useful options:

--add-drop-table: Tells MySQL to add a DROP TABLE statement before each CREATE TABLE in the dump.

--no-data: Dumps only the database structure, not the contents.

--add-locks: Adds the LOCK TABLES and UNLOCK TABLES statements you can see in the dump file.

The mysqldump command has advantages and disadvantages. The advantages of using mysqldump are that it is simple to use and it takes care of table locking issues for you. The disadvantage is that the command locks tables. If the size of your tables is very big mysqldump can lock out users for a long period of time.

b. With Compress backup:

Syntax: mysqldump -u [uname] -p[pass] [dbname] | gzip -9 > [backupfile.sql.gz]

For ex: mysqldump -u root -p renaisz7_renaissancedb | gzip -9 > renaisz7_renaissancedb.sql.gz

If you want to extract the .gz file, use the command below:

gunzip [backupfile.sql.gz]

Restoring your MySQL Database

Above we backup the Tutorials database into tut_backup.sql file. To re-create the Tutorials database you should follow two steps:

• Create an appropriately named database on the target machine
• Load the file using the mysql command:

mysql -u [uname] -p[pass] [db_to_restore] < [backupfile.sql]

Have a look how you can restore your tut_backup.sql file to the Tutorials database.

mysql -u root -p Tutorials < tut_backup.sql

To restore compressed backup files you can do the following:

gunzip < [backupfile.sql.gz] | mysql -u [uname] -p[pass] [dbname]

If you need to restore a database that already exists, you'll need to use mysqlimport command. The syntax for mysqlimport is as follows:

mysqlimport -u [uname] -p[pass] [dbname] [backupfile.sql]

Source: http://webcheatsheet.com/sql/mysql_backup_restore.php