체크박스 값을 db에 어떻게 입력하나요?

<tr>            <th scope="row"><label for="room_size_2">객실 타입 test</label></th>            <td> <input type="checkbox" name="room_size_2[]" value="농구" />농구 <input type="checkbox" name="room_size_2[]" value="축구" />축구 <input type="checkbox" name="room_size_2[]" value="배구" />배구 <input type="checkbox" name="room_size_2[]" value="야구" />야구            </td>         </tr>

<?php $room_size_2 = implode("|", $room_size_2) ; $sql_common = " room_type = $room_size_2 "; $sql =" UPDATE $write_table SET $sql_common WHERE wr_id ='$wr_id' ";sql_query($sql);