正如标题所说，我正试图使用mysqli fetch stmt从数据库中获取meta_keys和meta_values。我得到的错误是说内存不足，并在我的代码中引用了这一行：
//Bind result variables
$select_stmt->bind_result($id, $key, $value);
我真的不确定我做错了什么，这就是整个功能。我的目标是调用另一个文件中的函数，并传递我想要检索其meta_value的userID和选项（meta_key）。
function get_options($userid, $option) {
global $mysqli;
$query = "SELECT user_id, meta_key, meta_value FROM user_settings WHERE user_id = ? AND meta_key = ? LIMIT 4";
if($select_stmt = $mysqli->prepare($query)) {
$select_stmt->bind_param('ss', $userid, $option);
//Execute the prepared statement
$select_stmt->execute();
//Bind result variables
$select_stmt->bind_result($id, $key, $value);
//Fetch the values
while ($select_stmt->fetch()) {
printf($key, $value);
}
}
}
我明白了，以下是对我有效的方法，希望它能帮助其他人：
function get_options($userid, $option) {
global $mysqli;
if ($select_stmt = $mysqli->prepare("SELECT user_id, meta_key, meta_value, salt
FROM user_settings
WHERE user_id = ? AND meta_key = ?")) {
$select_stmt->bind_param('ss', $userid, $option);
$select_stmt->execute(); // Execute the prepared query.
$select_stmt->store_result();
// Execute the prepared query.
if (! $select_stmt->execute()) {
echo 'Could not perform option query on database';
}
// If the user exists get variables from result.
$select_stmt->bind_result($userID, $key, $value, $salt);
$select_stmt->fetch();
echo ' ID is '.$userID.'<br />';
echo ' Key is '.$key.'<br />';
echo ' Value is '.$value.'<br />';
echo ' Salt is '.$salt.'<br />';
} //end if($select_stmt)
}
在上面的内容中，您将看到我在绑定结果之前添加了store_result，并在绑定结果之后添加了fetch属性。