wp_redirect() is not working

My code is like below.

$result = $wpdb->query($sql);
    if ( $result ) {
      wp_redirect( "https://www.example.com/contact-us");
      exit();
    }

I am getting below error

Warning: Cannot modify header information - headers already sent by (output started at /var/www/html/wordpressplugin/wp-admin/includes/misc.php:1281) in /var/www/html/wordpressplugin/wp-includes/pluggable.php on line 1296

I tried with below code but I didn’t get any solution

$result = $wpdb->query($sql);
    if ( $result ) {
      ob_start();
      wp_redirect( "https://www.example.com/contact-us");
      ob_end_flush();
      exit();
    }

• This topic was modified 4 years, 3 months ago by abufoysal.
• This topic was modified 4 years, 3 months ago by bcworkz. Reason: code fixed