$records = array();

 if($results = $db->query("SELECT * FROM cust_tbl")) {
     if($results->num_rows) {
         while($row = $results->fetch_object()) {
             $records[] = $row;
         }

         echo json_encode($records);

         $results->free();
     }

 }

function show() {
    clear();
    $.ajax({
        type: "POST",
        dataType: "json",
        url: "process.php",
        data: "action=show",
        success: function(data) {
            $.each(data, function(index, data) {
                $('#tablebody').append('<tr>');
                $('#tablebody').append('<td>' + data.JL_JOB_DATE + '</td>');
                $('#tablebody').append('<td>' + data.JL_YR + '</td>');
                $('#tablebody').append('</tr>');
            });
        }
    });
}

$.each(data, function() {
    //use data.<column name>
});

$.each(data, function() {
    $('#tablebody').append( '' +
                            '<tr>' +
                                '<td>' + data.<column name> + '</td>' +
                                '<td>' + data.<column name> + '</td>' +
                            '</tr>' +
                            '');
});

escape_.escape(string)
Escapes a string for insertion into HTML, replacing &, <, >, ", and ' characters.

_.escape('Curly, Larry & Moe');
=> "Curly, Larry & Moe"

$.each(data, function(index, data) {
            $('#tablebody').append('<tr>');
            $('#tablebody').append('<td>' + escape(data.JL_JOB_DATE) + '</td>');
            $('#tablebody').append('<td>' + escape(data.JL_YR) + '</td>');
            $('#tablebody').append('</tr>');
        });