Question

      ... $tablename = $output2; 
      if($a==-1){   
       $query = "CREATE TABLE `" . $tablename . "` (
       `id` mediumint(9) NOT NULL AUTO_INCREMENT,
       `Name` varchar(60) NOT NULL,
       `Number` varchar(12) NOT NULL,
        PRIMARY KEY  (`id`)
        );"; 
       require_once(ABSPATH . 'wp-admin/includes/upgrade.php');
       dbDelta($query);
       }
       else{
       $wpdb->insert(
        $tablename, 
        array( 
            'Name' => $output, 
            'Number' => $output2,
             ), 
        array( 
            '%s',
            '%s',
                ) 
        );

       }

$output and $output2 are getting initialized fine. A table is being created with name $output2, but the values are not being inserted when ‘a’ holds any non-negative value. What am I doing wrong?

Answer 1

If a is a variable and not a defined constant, then there is an error in your code.
It should then be:

if($a==-1){