How to change the value of variable using if statement in php

I'm facing problems when I making an algorithm for my website.

I want to change the value of a variable using if, here is an snippet of my code.

    $description = $_GET['text1'];
    $first_p = $_GET['text2'];

    if($description == ""){
      $description = $first_p;
      $ins = mysqli($conn, "INSERT INTO mytable (description) VALUE ('$description')");
    }

Problem is that the value in description row not saving it will showing nothing means blank. Note: This code is a sample code not real.