This function give always 0 as result so I used ifx_affected_rows to count rows of a query's result...
An example of this function:
$conn_id = ifx_connect("db", "user", "password");
$res_id = ifx_query("select * from systables", $conn_id);
$res = ifx_affected_rows($res_id);
echo $res;
$res contains the number of rows in the result of the query after his execution.
Para Massimiliano