WordPress returns database errors when I submit a form

Question

<?php
//Template Name: download_form
get_header();
?>

<div id="primary" class="content-area">
    <main id="main" class="site-main">

    <form method="post">
        Full Name: <input type="TEXT" name="f_Name">
        <br><br>  
        Designation: <input type="TEXT" name="f_Desg">
        <br><br>
        Company Name: <input type="TEXT" name="f_Comp">
        <br><br>
        Address: <input type="TEXT" name="f_Addr">
        <br><br>

        <input type="SUBMIT" value="Submit" name="f_Submit">
    </form>

    <?php
        if(isset($_POST ['f_Submit']))
        {
            $name=$_POST ['f_Name'];

            $desg=$_POST['f_Desg'];
            $comp=$_POST['f_Comp'];
            $addr=$_POST['f_Addr'];

            global $wpdb;

            require_once( ABSPATH . 'wp-admin/includes/upgrade.php' );

            $table_name = $wpdb->prefix. 'ppex_downloadform_data';

            $wpdb->show_errors();

            $wpdb->insert(

                        array(''.table_name.'',
                            'person'    =>  $name,
                            'position'  =>  $desg, 
                            'comoany'   =>  $company,
                            'Address'   =>  $addr),
                            array(
                                '%s',
                                '%s',
                                '%s',
                                '%s', 
                                )
                            );

            if ($wpdb->insert_id) {echo "Data inserted successfully";}
            else {echo "An error occurred while saving data";
            }
        }
    ?>  
    </main><!-- #main -->
</div><!-- #primary -->

List of Errors

Warning: strtolower() expects parameter 1 to be string, array given in C:\xampp\htdocs\brgsite\wp-includes\wp-db.php on line 2802

Warning: strtolower() expects parameter 1 to be string, array given in C:\xampp\htdocs\brgsite\wp-includes\wp-db.php on line 2699

Warning: explode() expects parameter 2 to be string, array given in C:\xampp\htdocs\brgsite\wp-includes\wp-db.php on line 2724

Warning: implode(): Invalid arguments passed in C:\xampp\htdocs\brgsite\wp-includes\wp-db.php on line 2725

WordPress database error: [Incorrect table name ''] SHOW FULL COLUMNS FROM `` An error occurred while saving data

Answer 1

You might want to use the variable $table_name instead of the text table_name :)

You can also remove '' and ., since adding an empty string at the beginning and the end is pointless :)

$wpdb->insert( array($table_name, ... ) );