.fixed-table {
    table-layout: fixed;
}

/* FOR CORPORATE DATA TABLE START */
function format ( dataSource ) {
    var html = '<table cellpadding="5" cellspacing="0" border="0" style="padding-left:50px;" class="fixed-table table table-bordered">';
    for (var key in dataSource){
        html += '<tr>'+
                   '<td>' + key             +'</td>'+
                   '<td>' + dataSource[key] +'</td>'+
                '</tr>';
    } return html += '</table>';  }
var earnings_amendment_table = $('#earnings_amendment').DataTable({});

      // Add event listener for opening and closing details
      $('#earnings_amendment').on('click', 'td.details-control', function () {
          var tr = $(this).closest('tr');
          var row = earnings_amendment_table.row(tr);

          if (row.child.isShown()) {
              // This row is already open - close it
              row.child.hide();
              tr.removeClass('shown');
          } else {
              // Open this row
              row.child(format({
                  'Particulars : ' : tr.data('key-1'),
                  'Account Type : ' : tr.data('key-2'),
                  'Date Due : ' :  tr.data('key-3')
              })).show();
              tr.addClass('shown');
          } });
/* FOR CORPORATE DATA TABLE END */

<div class="box-body">
              <table id="earnings_amendment" class="fixed-table table table-bordered">
                <thead>
                  <th></th>
                  <th>Reference ID.</th>
                  <th>Reference No.</th>
                  <th>Employee Name</th>
                  <th>Account Title</th>
                  <th>Amount</th>
                  <th>Activity</th>
                  <th>Posted By</th>
                  <th>Validated By</th>
                  <th>Noted By</th>
                  <th>Tools</th>
                </thead>
                <tbody>
                <?php
$sql = "
select earningsamendment.particulars,earningsamendment.accounttype,earningsamendment.datedue,
employeemasterfile.lastname,employeemasterfile.firstname,employeemasterfile.middlename,
referenceno, accounttitle, max(credit) as credit, max(debit) as debit, max(referenceid) as referenceid, earningsamendment.employeeidno,
earningsamendment.postedby, approvedby, notedby
from earningsamendment
left join employeemasterfile on earningsamendment.employeeidno= employeemasterfile.employeeidno
WHERE earningsamendment.accounttitle='$accounttitle' AND
YEAR(earningsamendment.dateposted)='$year'
group by referenceno, earningsamendment.employeeidno, accounttitle, earningsamendment.postedby, approvedby,
notedby,employeemasterfile.lastname,employeemasterfile.firstname,employeemasterfile.middlename,
earningsamendment.particulars,earningsamendment.accounttype,earningsamendment.datedue
";
                    $query = sqlsrv_query($conn, $sql, array(), array("Scrollable" => SQLSRV_CURSOR_KEYSET));
                    while($row = sqlsrv_fetch_array($query, SQLSRV_FETCH_ASSOC)){
                      echo "
                      <tr data-key-1='".$row['particulars']."' data-key-2='".$row['accounttype']."' data-key-3='".$row['datedue']."'>
                        <td class='details-control'></td>
                          <td>".$row['referenceid']."</td>
                          <td>".$row['referenceno']."</td>
                          <td>".$row['lastname']." ".$row['middlename']." ".$row['firstname']."</td>
                          <td>".$row['accounttitle']."</td>
                          <td>".$row['credit']."</td>
                          <td>".(($row['debit']==$row['credit']) ? 'PAID' : 'FOR TAKE UP' )."</td>
                          <td>".$row['postedby']."</td>
                          <td>".$row['approvedby']."</td>
                          <td>".$row['notedby']."</td>
                          <td>
                            <button class='btn btn-success btn-sm edit btn-flat' data-id='".$row['referenceid']."'><i class='fa fa-edit'></i> Preview</button>

                            <button class='btn btn-danger btn-sm delete btn-flat' data-id='".$row['referenceid']."'><i class='fa fa-trash'></i> Delete</button>

                        " ?>
                            <?php if (empty($row['approvedby'])) { echo " <button class='btn btn-warning btn-sm approve btn-flat' data-id='".$row['referenceid']."'><i class='fa fa-check-square-o'></i> Approve</button> "; } ?>

                            <?php if (empty($row['notedby'])) { echo " <button class='btn btn-primary btn-sm note btn-flat' data-id='".$row['referenceid']."'><i class='fa fa-arrow-circle-right'></i> Note</button> "; } ?>

                            <?php "</td>
                        </tr>
                      ";
                    }
                  ?>
                </tbody>
              </table>
            </div>