Формат JSON для создания динамической сетки столбцов Jqwidgets

Я не могу получить правильный формат JSON для создания динамической сетки столбцов.
Вот что у меня есть:
PHP

$query="select * from mytable";
$rs = mysql_query($query);
$rows = array();
while($r = mysql_fetch_object($rs)) {
$rows[] = $r;
}
echo json_encode($rows);

//Results:
[{"EmpID":"12345","Name":"James","Account":"New Account1","Group1":"Library","Food_Bill_Date":null,"Food_Bill_Amount":null,"Food_Bill_Number":null},
{"EmpID":"12346","Name":"David","Account":"New Account2","Group2":"Lab","Food_Bill_Date":null,"Food_Bill_Amount":null,"Food_Bill_Number":null},
{"EmpID":"12347","Name":"Ramsy","Account":"New Account2","Group2":"Lab","Food_Bill_Date":null,"Food_Bill_Amount":null,"Food_Bill_Number":null},
............
.............
............
]

Динамическая колонка Jqwidgets

Необходимо отделить строки и столбцы от массива результатов.

Требуется в

[
{
"columns": [
{
"text": "SampleK",
"datafield": "sample1",
"width": "30"},
{
"text": "ID",
"datafield": "id",
"width": "30"}
]
}
{
"rows": [
{
"id": "1",
"name": "Hot Chocolate",
"type": "Chocolate Beverage",
"calories": "370",
"totalfat": "16g",
"protein": "14g"},
{
"id": 2,
"name": "Peppermint Hot Chocolate",
"type": "Chocolate Beverage",
"calories": "440",
"totalfat": "16g",
"protein": "13g"},
]
}
]

Пожалуйста помоги.