PHP mysqli_fetch_assoc（）函数在相同的PHP文件工作时返回NULL

Question

i have spent a day now but i am not able to solve the following problem. I have this code to access my database and i want to get some values. The weird thing is, that the same code works for the same php file on the same server in the same directory. I wanted to create a new php file with a different sql selection, but this one always returns null instead of a json array.

Any helpful advice would be great! I am running a wordpress site, maybe thats an important information.

<?php
if( isset( $_POST[user_id] ) )
{
    $user_id = $_POST[user_id];

    $servername = "****";
    $username = "****";
    $password = "****";
    $dbname = "****";

    // Create connection
    $conn = new mysqli($servername, $username, $password, $dbname);

    // Check connection
    if ($conn->connect_error) {
        die("Connection failed: " . $conn->connect_error);
    } 
    //echo "Connected successfully";
    //echo $user_id;


    $sql = "SELECT *
    FROM felderkonfig
    WHERE felderkonfig_user_id = '$user_id' ";

    $result = mysqli_query($conn, $sql);    //sql abfrage in array speichern
    $myArray = array();
    $myArray =mysqli_fetch_assoc($result);  //umwandeln in assoziatives array

    echo json_encode($myArray);     //echo als json array


    $conn->close();
    exit(); 
}else{
    echo "Fehler bei if isset";     
}
?>

Answer 1

You should include this file to the prefered php file like where ever you want to connect the database

<?php include 'connect.php' ?>

in connect.php file should have the connection settings like what you metioned in the question exluded selct query