我正在使用mysql托管数据库，并检查"收藏夹"表中是否存在条目。当用户点击喜爱的按钮时，会填充该表。当我在poster上运行查询时，我会回显查询的结果，即使数据库中存在条目，我也会返回NULL。
$conn = mysqli_connect($servername, $username, $password,$db);
// Check connection
if ($conn->connect_error) {
die("Connection failed: " . $conn->connect_error);
}
// json response array
$response = array("error" => FALSE);
if (isset($_POST['memory_id']) && isset($_POST['uid'])) {
// receiving the post params
$memory_id=$_POST['memory_id'];
$user_id=$_POST['uid'];
echo $memory_id;
echo $user_id;
$result = mysqli_query($conn, "SELECT * FROM favorite WHERE memory_id='$memory_id' AND user_id='$user_id'");
if($result)
{
echo json_encode($result);
// user failed to store
$response["favorite"] = TRUE;
echo json_encode($response);
}
else {
$response["favorite"]=FALSE;
echo json_encode($response);
}
}
else {
$response["error"] = TRUE;
$response["error_msg"] = "Required parameters user or memory is missing!";
echo json_encode($response);
}
mysqli_close($conn);
?>
也许您忘记调用一些mysqli获取函数（如mysqli_fetch_assoc）：
$q = mysqli_query($conn, "SELECT * FROM favorite WHERE memory_id='$memory_id' AND user_id='$user_id'");
$result = mysqli_fetch_assoc($q);
if($result)
{
echo json_encode($result);
......
注意：假设您的收藏夹：：memory_id和收藏夹：：user_id列是VARCHAR类型