why datatables sorting is not working at right place?

I have posted picture. I am not getting datatables sorting on first tr tag. I have datatables individual column searching with select on second tr tag... but i want sorting on 1st tr tag and using scripts of theme dashboard working on theme but not woking on my project.Posted Picture for clear concept.

<script src="https://code.jquery.com/jquery-3.3.1.js"></script>
<script src="" type="text/javascript"></script>
<link rel="stylesheet" type="text/css" href="">

Blade

<div class="card-content collapse show">
      <div class="table-responsive" id="searchResult">
          <table class="table table table-striped table-bordered base- 
          style" id="myTable">
    <thead class="table table-striped">
<tr>
    <th>Supplier Name</th>
    <th>Item Name</th>
    <th>Quantity</th>
    <th>Price</th>
    <th>Total</th>
    <th>Purchase Date</th>
    <th>Actions</th>
</tr>
<tr>
    <th></th>
    <th></th>
    <th></th>
    <th></th>
    <th></th>
    <th></th>
    <th></th>
</tr>
</thead>
<tbody>
@foreach($allPurchases as $purchase)
    <tr>
        <td></td>
        <td></td>
        <td></td>
        <td></td>
        <td></td>
        <td></td>
        <td><a onclick="edit_purchases()"><i style="font-size: 18px" class="far fa-edit"></i>
            </a> | <a
                    href=""><i style="color: red;font-size: 18px" class="far fa-trash-alt"></i>

            </a>
        </td>
    </tr>
@endforeach
</tbody>
</table>
</div>
</div>

Script:

<script>
    var dataTableList = "";

    $(document).ready(function () {
        dataTableList = $('#myTable').DataTable({
            initComplete: function () {
                this.api().columns([0,1]).every( function () {
                    var column = this;
                    var select = $('<select><option value=""></option></select>')
                        .appendTo( $(column.header()))
                        .on( 'change', function () {
                            var val = $.fn.dataTable.util.escapeRegex(
                                $(this).val()
                            );

                            column
                                .search( val ? '^'+val+'$' : '', true, false )
                                .draw();
                        } );

                    column.data().unique().sort().each( function ( d, j ) {
                        select.append( '<option value="'+d+'">'+d+'</option>' )
                    } );
                } );
            },
        });
    });
</script>

via Chebli Mohamed