php – Learn how to add Overseas key to submit kind

I’m making an attempt so as to add a international key to a submit kind. I made a submit kind that provides knowledge to the database, however am uncertain how one can add the international key. I made the var $Address_ID, which is the closest I’ve gotten to date.

Right here is the front-end kind:

<kind technique="put up">
     <!-- CENTRAL_ADDRESS -->
        <label for="Add1">Add1: </label><br>
        <enter kind="textual content" id="Add1" identify="Add1"><br>

        <label for="Add2">Add2: </label><br>
        <enter kind="textual content" id="Add2" identify="Add2"><br><br>

        <label for="Metropolis">Metropolis:</label><br>
        <enter kind="textual content" id="Metropolis" identify="Metropolis"><br><br>

        <label for="State">State:</label><br>
        <enter kind="textual content" id="State" identify="State"><br><br>

        <label for="Zip">Zip</label><br>
        <enter kind="textual content" id="Zip" identify="Zip"><br><br>

        <label for="Telephone">House Telephone:</label><br>
        <enter kind="textual content" id="Telephone" identify="Telephone"><br><br>

        <label for="E-mail">E-mail Handle:</label><br>
        <enter kind="textual content" id="E-mail" identify="E-mail"><br><br>
        
        
        
        <!-- CENTRAL_STUDENT -->
        <label for="First_Name">First Identify: </label><br>
        <enter kind="textual content" id="First_Name" identify="First_Name"><br>

        <label for="Last_Name">Final Identify: </label><br>
        <enter kind="textual content" id="LAst_Name" identify="Last_Name"><br>
        
        <label for="Middle_Name">Center Identify: </label><br>
        <enter kind="textual content" id="Middle_Name" identify="Middle_Name"><br>

        <enter kind="submit" identify="nameBtn" worth="submit">

    </kind>

</kind>

Right here is the backend kind:

if(isset($_POST['nameBtn']))
    {
        world $wpdb;
        
        // CENTRAL_ADDRESS
        $Add1 = sanitize_text_field($_POST['Add1']);
        $Add2 = sanitize_text_field($_POST['Add2']);
        $Metropolis = sanitize_text_field($_POST['City']);
        $State = sanitize_text_field($_POST['State']);
        $Zip = sanitize_text_field($_POST['Zip']);
        $Telephone = sanitize_text_field($_POST['Phone']);
        $E-mail = sanitize_text_field($_POST['Email']);

        // CENTRAL_STUDENT
        $First_Name = sanitize_text_field($_POST['First_Name']);
        $Last_Name = sanitize_text_field($_POST['Last_Name']);
        $Middle_Name = sanitize_text_field($_POST['Middle_Name']);

        //Overseas Key displayed beneath Central_Student. Factors to ID key within the Central_Address desk
        $Address_ID = $wpdb->question("FOREIGN KEY (Address_ID) REFERENCES" .'Central_Address'. " (ID)");
        
        
        // Central_Student Desk
        $wpdb->insert('Central_Student', array('First_Name'=>$First_Name, 'Last_Name'=>$Last_Name, 'Middle_Name'=>$Middle_Name, $Address_ID));
        
        //Central_Address Desk
        $wpdb->insert('Central_Address', array('Add1'=>$Add1, 'Add2'=>$Add2, 'Metropolis'=>$Metropolis, 'State'=>$State, 'Zip'=>$Zip, 'E-mail'=>$E-mail, 'Telephone'=>$Telephone));


    }

There are two tables during which I’m making an attempt so as to add knowledge: Central_Student, and Central_Address.

Central_Address fields: ID(PK and hidden), Add1, Add2, Metropolis, State, Zip, E-mail and Telephone.

Central_Student fields: Address_ID(FOREIGN KEY), First_Name, Last_Name, and Middle_Name.

After the submit button, the ID from the Central_Address desk needs to be displayed as a international key as the sector Address_ID within the desk Central_Student. However I have no idea how one can implement this. Any strategies could be tremendously appreciated.