entering checkbox value into mysql

i have the following checkboxes

<input type="checkbox" name="weekday[]" value="Monday" /> Monday &nbsp;&nbsp;&nbsp;
<input type="checkbox" name="weekday[]" value="Tuesday" /> Tuesday &nbsp;&nbsp;&nbsp;
<input type="checkbox" name="weekday[]" value="Wednesday" /> Wednesday </br>
<input type="checkbox" name="weekday[]" value="Thursday" /> Thursday &nbsp;&nbsp;&nbsp;
<input type="checkbox" name="weekday[]" value="Friday" /> Friday &nbsp;&nbsp;&nbsp;
<input type="checkbox" name="weekday[]" value="Saturday" /&开发者_运维问答gt; Saturday &nbsp;&nbsp;&nbsp;
<input type="checkbox" name="weekday[]" value="Sunday" /> Sunday &nbsp;&nbsp;&nbsp;

I would like to enter all the checked values into "day" field in mysql separated by coma,

please help

How about

implode(',',$_POST['weekday'])

?

   if(isset($_POST['submit_btn_name']))
   {
      $days="";

      if(isset($_POST['weekday']))
      {

          foreach($_POST['weekday'] as $id)
          {
                $days.=$id.",";
          }
              $days = substr($days, 0, -1);

      }

      echo $days;

   }

EDIT this is in response to the comment about the query to post the $days variable as I found it difficult to format code in the comments.

  $sql1=mysql_query("INSERT INTO class (class_id, subject_id, student_id, available_days, available_time, status) VALUES ('".$class_id."','".$subject_id."','".$student_id."','".$days."','".$available_t‌​ime."','pending')"‌​)or die('Error: There was error while submitting the schedule, please try again.');

you will get $_POST['weekday'] as an array. you can use it like

$_POST['weekday'][0];
$_POST['weekday'][1];
$_POST['weekday'][2];
$_POST['weekday'][3];
$_POST['weekday'][4];
$_POST['weekday'][5];
$_POST['weekday'][6];

For searching you should implode(',' , $_POST['weekday']) and use

$sql = "select * from table where day in ('" . implode("','" , $_POST['weekday']) . "')"; 

in sql query

You can do like this:

$arr = array();

// check for CHECKED checkboxes
for(var $i = 0; $i > count($_POST['weekday']); $i++){
   // if this checkbox is checked
   if (isset($_POST['weekday'][$i])) { 
       $arr[] = $_POST['weekday'][$i];
   }
}

// convert to comma separated
$checkbox_str = implode(',', $arr);

Now you can use $checkbox_str to save in the database.