How to get current user_id of logged in user

Question

I just created a php file to update a field in mysql db, my update query is where i have an issue, i want to set 'user_id' to be the user_id of the current user that is logged in so the update will go to the appropriate user. I haven't been able to get this to work. I feel its because i haven't declared the current user earlier in the code, how can i do this?

Here is the line:

$sql = "UPDATE wp85_usermeta SET `meta_value` = `meta_value`+65000 WHERE `user_id` = user_id AND `meta_key` = 'mycred_default'"

Here is the full code:

<?php
    $servername = "localhost";
    $username = "sparyqmr_wp324";
    $password = "(S8p3uV-2t";
    $dbname = "sparyqmr_wp324";

    // Create connection
    $conn = new mysqli($servername, $username, $password, $dbname);
    // Check connection
    if ($conn->connect_error) {
        die("Connection failed: " . $conn->connect_error);
    }

    $sql = "UPDATE wp85_usermeta SET `meta_value` = `meta_value`+65000 WHERE `user_id` = user_id AND `meta_key` = 'mycred_default'";

    if ($conn->query($sql) === TRUE) {
        echo "Record updated successfully";
    } else {
        echo "Error updating record: " . $conn->error;
    }

    $conn->close();
?>

Answer 1

Try to use Session variables. Session varibles are globals variables which are stored on the server for each user.

If a user log ins, you can store his userid in a session varible. If the session is started, you can access this varible in all your documents.

You can start a session with:

session_start();

You can set a session variable, with the following code:

$_SESSION['userid'] = 'your_user';

Answer 2

Logged in user info is in WP Session Cookies .

Example:

    foreach ($_COOKIE as $k => $v) {
        if ( preg_match( "/wordpress_logged_in/", $k ) ) {
            // DO SOMETHING WITH THIS COOKIE
        } // end if matched login cookie
} // end foreach

Answer 3

I was able to solve this adding the following to the top of my code

require ('wp-blog-header.php');

global $wpdb;

global $current_user;
get_currentuserinfo();

$skrivID = $current_user->ID;

using $skrivID later in the code automatically returned the user id of the logged in user