$wpdb->insert() is giving error undefined function

Question

I have created a new file inside wp-content/theme/mytheme folder.

Inside the file I have written simple query

global $wpdb;
    $insert= $wpdb->i         


        

Answer 1

By these ways , You can do it easily,

First define $wpdb globally as like global $wpdb;

require_once('../wp-load.php'); // relative path

insert("wp_submitted_form", array(
   "col_nmae" => $value,
 ));
?>

Second Way is

$sql = $wpdb->prepare(
    "INSERT INTO `wp_submitted_form`    
       (col_nmae) 
 values ($val)");
$wpdb->query($sql);

Third is

$sql = "INSERT INTO `wp_submitted_form`
          (col_nmae) 
   values ($val)";

$wpdb->query($sql);

If you are beginner then read more here https://codex.wordpress.org/Class_Reference/wpdb