php - 简化: mysqli num_rows not working

Question

如何使用 mysqli 输出返回的行数？我下面的代码显示 0，尽管 while 循环 (while $s->fetch() echo $uid;) 显示 2 个结果；

$m = new mysqli(MYSQL_SERVER, MYSQL_USER, MYSQL_PASS, MYSQL_DB);
$s=$m->prepare("SELECT uid FROM user WHERE token=? AND secret=?");
$s->bind_param('ss',$rt, $rs);
$rt='c';
$rs='d';
$s->execute();
$s->bind_result($uid);
$s->fetch();
print_r($s->num_rows); // RESULTS IN 0

Answer 1

您必须在 mysqli_stmt::execute() 之后和 fetch 之前调用 mysqli_stmt::store_result() 才能知道 mysqli_stmt::num_rows :

$s->execute();
$s->store_result();
print_r($s->num_rows);

PHP Document on num_rows

PHP Document on store_result()