Create a checkbox with two choices in on database table

I have created a checkbox,what database table will I need to save in the numbers ? example of what I am thinking of, to create a table with a name mytable so I will have

id  pos  
1   13     
2   14

if someone check the 14 to be like a then

id  pos  pawn
1   13    
2   14     a

if someone check the 13 to be b then

id   pos  pawn
 1    13    b
 2    14    a

if someone check for example 13 to be a and b ,so I will have

id   pos   pawn
1    13    a b
2    14

I tried

CREATE TABLE `mytable` (
`id` numeric(24) DEFAULT NULL,
`position` numeric(24) DEFAULT NULL,
`last_action` timestamp NOT NULL DEFAULT current_timestamp() ON UPDATE current_timestamp()
)

the code of doing that is this on my index.php.Only two ticks allowed. 1 tick for a ,13 until 24 and 1 tick for b ,13 until 24.I didn't managed to do that.

<form action="index.php" method="post">
  13<input type="checkbox" name="check_list[]" value="value 1"> a
    <br>
  14  <input type="checkbox" name="check_list[]" value="value 2">a
    <br>
 15   <input type="checkbox" name="check_list[]" value="value 3">a
    <br>
  16  <input type="checkbox" name="check_list[]" value="value 4">a
    <br>
17    <input type="checkbox" name="check_list[]" value="value 5">a
    <br>
18  <input type="checkbox" name="check_list[]" value="value 6">a
    <br>
19  <input type="checkbox" name="check_list[]" value="value 7">a
    <br>
20  <input type="checkbox" name="check_list[]" value="value 8">a
    <br>
21  <input type="checkbox" name="check_list[]" value="value 9">a
    <br>
22  <input type="checkbox" name="check_list[]" value="value 10">a
    <br>
23  <input type="checkbox" name="check_list[]" value="value 11">a
    <br>
24  <input type="checkbox" name="check_list[]" value="value 12">a
    <br>
    
    
    
    
    
    
     13<input type="checkbox" name="check_list[]" value="value 1"> b
    <br>
  14  <input type="checkbox" name="check_list[]" value="value 2">b
    <br>
 15   <input type="checkbox" name="check_list[]" value="value 3">b
    <br>
  16  <input type="checkbox" name="check_list[]" value="value 4">b
    <br>
17    <input type="checkbox" name="check_list[]" value="value 5">b
    <br>
18  <input type="checkbox" name="check_list[]" value="value 6">b
    <br>
19  <input type="checkbox" name="check_list[]" value="value 7">b
    <br>
20  <input type="checkbox" name="check_list[]" value="value 8">b
    <br>
21  <input type="checkbox" name="check_list[]" value="value 9">b
    <br>
22  <input type="checkbox" name="check_list[]" value="value 10">b
    <br>
23  <input type="checkbox" name="check_list[]" value="value 11">b
    <br>
24  <input type="checkbox" name="check_list[]" value="value 12">b
    <br>
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    <button    type="submit" onclick="transfertoanotherpage()"  class='btn btn-primary'> End of turn</button>
    
</form>




<?php
if(!empty($_POST['check_list'])) {
    foreach($_POST['check_list'] as $check) {
            echo $check;
    }
}
?>

</div>