Syntax:
CHECKSUM TABLE tbl_name [, tbl_name] ... [ QUICK | EXTENDED ]

CHECKSUM TABLE reports a table checksum. During the checksum operation,
the table is locked with a read lock for InnoDB and MyISAM. This
statement requires the SELECT privilege for the table.

This statement is not supported for views. If you run CHECKSUM TABLE
against a view, the Checksum value is always NULL, and a warning is
returned.

With QUICK, the live table checksum is reported if it is available, or
NULL otherwise. This is very fast. A live checksum is enabled by
specifying the CHECKSUM=1 table option when you create the table;
currently, this is supported only for MyISAM tables. See [HELP CREATE
TABLE].

With EXTENDED, the entire table is read row by row and the checksum is
calculated. This can be very slow for large tables.

If neither QUICK nor EXTENDED is specified, MySQL returns a live
checksum if the table storage engine supports it and scans the table
otherwise.

For a nonexistent table, CHECKSUM TABLE returns NULL and generates a
warning.

In MySQL 5.5, CHECKSUM TABLE returns 0 for partitioned tables unless
you include the EXTENDED option. This issue is resolved in MySQL 5.6.
(Bug #11933226, Bug #60681)

The checksum value depends on the table row format. If the row format
changes, the checksum also changes. For example, the storage format for
temporal types such as TIME, DATETIME, and TIMESTAMP changes in MySQL
5.6 prior to MySQL 5.6.5, so if a 5.5 table is upgraded to MySQL 5.6,
the checksum value may change.

URL: http://dev.mysql.com/doc/refman/5.5/en/checksum-table.html

