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(), and dba_replace().