Syntax:
SHOW OPEN TABLES [{FROM | IN} db_name]
    [LIKE 'pattern' | WHERE expr]

SHOW OPEN TABLES lists the non-TEMPORARY tables that are currently open
in the table cache. See
http://dev.mysql.com/doc/refman/5.1/en/table-cache.html. The WHERE
clause can be given to select rows using more general conditions, as
discussed in http://dev.mysql.com/doc/refman/5.1/en/extended-show.html.

The FROM and LIKE clauses may be used beginning with MySQL 5.1.24. The
LIKE clause, if present, indicates which table names to match. The FROM
clause, if present, restricts the tables shown to those present in the
db_name database.

URL: http://dev.mysql.com/doc/refman/5.1/en/show-open-tables.html

