所以，我有一个准备好的语句，我已经成功地准备、绑定和执行了：
SELECT * FROM users WHERE email = ? AND pass = SHA1(?)
看起来像预期的那样返回了一行。但是，为什么当我调用@ $stmt->get_result()时$result变量为空？提前谢谢。
$num_rows = mysqli_num_rows($stmt->get_result());
if ($num_rows == 1) {
// Fetch the result set
$result = $stmt->get_result();
//if result empty echo false
if(empty($result)) {
echo "result is empty";
}
}
只是为了把两个评论放在一起，并详细说明一个点......
<?php
$result = $stmt->get_result();
$num_rows = mysqli_num_rows($result);
if ($num_rows == 1) {
// already fetched the mysqli_result
// now lets fetch the one record from that result set
$row = $result->fetch_assoc();
// ....do something with row
}
else {
// either 0 ...or more than 1 row
foo();
}
但是你甚至可以摆脱对 mysqli_num_rows（） 的调用（所以它在未缓冲查询的情况下也有效）
$result = $stmt->get_result();
$row = $result->fetch_assoc();
if ( !$row ) {
// no such record
foo();
}
else {
// ....do something with row
// might want to check whether there are more matching records
// given the context there shouldn't, but ...
}