<?php
   $servername = "localhost";
   $username = "root";
   $password = "";
   $dbname = "run";


   $conn = mysqli_connect($servername, $username, $password, $dbname);

   $start = $_POST['start'];       //this is from html form

       $get = "SELECT distance FROM runs WHERE start='City' ";      //2nd error
       $show = mysqli_query($conn, $get);

      echo($show);      //1st error

   mysqli_close($conn);
 ?>

$get = "SELECT distance FROM runs WHERE start="City" ";