Generating information based on choice from radio buttons in php

I have some information stored in a database which is picked up and displayed with radio buttons. I would like to display information from the database based on what radio buttons have been chosen. For example I have a list of activities a someone may have done and based on what they have chosen I would like to display other activities they could do. I can get the system to display random information from the database using RAND() but not from what radio buttons have been selected. Can't find any online tutorials for this.

Here is my code.

              <?php 

                $query1 = "SELECT Name FROM activities WHERE ID = 1"
      $result1 = mysqli_query($con, $query1) or die("Invalid Query");

      while($row1 = mysqli_fetch_assoc($result1)){ 
        
        $name = $row1["Name"];


echo "<input type=\"checkbox\" name=\"city\" value=\"$name\" />$name </br>";
        
        }

        $query2 = "SELECT Name FROM activities WHERE ID = 2";

    
      $result2 = mysqli_query($con, $query2) or die("Invalid Query");

      while($row2 = mysqli_fetch_assoc($result2)){ 
        
        $name = $row2["Name"];


echo "<input type=\"checkbox\" name=\"city\" value=\"$name\" />$name </br>";
        
        }

                $query3 = "SELECT Name FROM activities WHERE ID = 3";

    
      $result3 = mysqli_query($con, $query3) or die("Invalid Query");

      while($row3 = mysqli_fetch_assoc($result3)){ 
        
        $name = $row3["Name"];


echo "<input type=\"checkbox\" name=\"city\" value=\"$name\" />$name </br>";
        
        }


$query4 = "SELECT Name FROM activities WHERE ID = 4";

    
      $result4 = mysqli_query($con, $query4) or die("Invalid Query");

      while($row4 = mysqli_fetch_assoc($result4)){ 
        
        $name = $row4["Name"];


echo "<input type=\"checkbox\" name=\"city\" value=\"$name\" />$name </br>";
        
        }

?>

<?php

$query= "SELECT * FROM activities ORDER BY RAND() LIMIT 1";

$result = mysqli_query($con, $query2) or die("Invalid Query");

      while($row2 = mysqli_fetch_assoc($result)){ 

$activities = $row["Name"];

echo "<p>$activities</p>";

        }

?>