bool dba_exists(string key, int handle);dba_exists() checks whether the specified key exists in the database specified by handle.
key is the key the check is performed for.
handle is a database handle returned by dba_open().
dba_exists() returns true or false, if the key is found or not found, respectively.
See also: dba_fetch() dba_delete() dba_insert() dba_replace()