The 'mysqldump' command is used to dump databases managed by MySQL. Let's consider three the most useful cases of MySQL database dumping.
The simplest case is the whole database dumping:
mysqldump -u username -ppassword database_name > the_whole_database_dump.sql
Sometimes, there's a need to dump a single table from your database. You can do it in the next way:
mysqldump -u username -ppassword database_name table_name > single_table_dump.sql
You can also specify several tables separated by whitespace to dump these tables only.
If you want to dump only rows that meet a specific criteria, you can add 'where' option to your mysqldump command. For example, dump only rows where date_created is today:
mysqldump -u username -ppassword database_name table_name --where="date_created='2013-06-25'" > few_rows_dump.sql