尽管存在条目，查询返回零行

Question

我在下面有这些准备好的陈述。我执行执行并返回1，意味着查询成功，但num_rows仍为零。我不知道为什么。有什么想法吗？

$ustmt = $bd->prepare("SELECT * FROM member WHERE username = ?");
$ustmt->bind_param("s", $username);

$astmt = $bd->prepare("SELECT address FROM member WHERE address = ?");
$astmt->bind_param("s", $address);

$sql = $ustmt->execute();
$sql2 = $astmt->execute();

echo($sql2);
echo($sql);

echo($ustmt->num_rows);
echo($astmt->num_rows);

Answer 1

我忘了添加store_result（）;我执行完毕后我浪费了很多时间！