Playing with mysqldump

If you have either a shell or telnet access to your database server, you can backup the database using mysqldump. By default, the output of the command will dump the contents of the database in SQL statements to your console. This output can then be piped or redirected to any location you want. If you plan to backup your database, you can pipe the output to a sql file, which will contain the SQL statements to recreate and populate the database tables when you wish to restore your database. There are more adventurous ways to use the output of mysqldump.

A Simple Database Backup:

You can use mysqldump to create a simple backup of your database using the following syntax.

mysqldump -u [username] -p [password] [databasename]> [backupfile.sql]

[username] – this is your database username
[password] – this is the password for your database
[databasename] – the name of your database
[backupfile.sql] – the file to which the backup should be written.

The resultant dump file will contain all the SQL statements needed to create the table and populate the table in a new database server. To backup your database ‘Customers’ with the username ‘sadmin’ and password ‘pass21′ to a file custback.sql, you would issue the command:

mysqldump -u sadmin -p pass21 Customers> custback.sql

You can also ask mysqldump to add a drop table command before every create command by using the option –add-drop-table. This option is useful if you would like to create a backup file which can rewrite an existing database without having to delete the older database manually first.

mysqldump –add-drop-table -u sadmin -p pass21 Customers> custback.sql

Backing up only specified tables

If you’d like restrict the backup to only certain tables of your database, you can also specify the tables you want to backup. Let’s say that you want to backup only customer_master & customer_details from the Customers database, you do that by issuing

mysqldump –add-drop-table -u sadmin -p pass21 Customers customer_master customer_details> custback.sql

So the syntax for the command to issue is:

mysqldump -u [username] -p [password] [databasename] [table1 table2 ....]

[tables] – This is a list of tables to backup. Each table is separated by a space.

If you are a database administrator who has to look after multiple databases, you’ll need to back up more than one database at a time. Here’s how you can backup multiple databases in one shot.

If you want to specify the databases to backup, you can use the –databases parameter followed by the list of databases you would like to backup. Each database name has to be separated by at least one space when you type in the command. So if you have to backup 3 databases, let say Customers, Orders and Comments, you can issue the following command to back them up. Make sure the username you specify has permissions to access the databases you would like to backup.

mysqldump -u root -p pass21 –databases Customers Orders Comments> multibackup.sql

This is okay if you have a small set of databases you want to backup. Now how about backing up all the databases in the server? That’s an easy one, just use the –all-databases parameter to backup all the databases in the server in one step.

mysqldump –all-databases> alldatabases.sql