$id = dba_open("bdb4_tsid.db", "w", "db4");

if (!$id) { echo "dba_open failed\n"; exit; }

dba_replace("key", "This is an example!", $id);

if (dba_exists("key", $id)) {
        echo dba_fetch("key", $id);
        dba_delete("key", $id);
}

dba_close($id);

This is an example!
exist:
This is an example!
---> This is an example!