<?php
$conn = cubrid_connect("localhost", 33000, "demodb");
$sql = <<<EOD
SELECT host_year, medal, game_date 
FROM game 
WHERE athlete_code IN 
    (SELECT code FROM athlete WHERE name='Thorpe Ian');
EOD;
$req = cubrid_execute($conn, $sql, CUBRID_INCLUDE_OID);
$oid = cubrid_current_oid($req);
$res = cubrid_is_instance ($conn, $oid);
if ($res == 1) {
    echo "Instance pointed by $oid exists.\n";
} else if ($res == 0){
    echo "Instance pointed by $oid doesn't exist.\n";
} else {
    echo "error\n";
}
cubrid_disconnect($conn);
?>
    
    The above example will output:
Instance pointed by @0|0|0 doesn't exist.