/*      fetch_fields()       */
static VALUE fetch_fields(VALUE obj)
{
    MYSQL_RES* res;
    MYSQL_FIELD* f;
    unsigned int n;
    VALUE ret;
    unsigned int i;
    check_free(obj);
    res = GetMysqlRes(obj);
    f = mysql_fetch_fields(res);
    n = mysql_num_fields(res);
    ret = rb_ary_new2(n);
    for (i=0; i<n; i++)
        rb_ary_store(ret, i, make_field_obj(&f[i]));
    return ret;
}