Php ODBC更改json数组格式

我正在使用ms access odbc获取sql数据。但是我没有得到我想要的结果。这是我的密码：

$rs = odbc_exec($con, $sql);
if (!$rs) {
    exit("There is an error in the SQL!");
}
$data[0] = array('D','CPU_Purchased_ghz');
$i = 1;

while($row = odbc_fetch_array($rs)) {
    $data[$i] = $row;
    $i++;
}

odbc_close($con); // Closes the connection
$json = json_encode($data); // Generates the JSON, saves it in a variable
echo $json;

我获得结果的方式如下：

[
    ["D","CPU_Purchased_ghz"],
    {"D":"2015-03-14 00:00:00","CPU_Purchased_ghz":"10.00"},
    {"D":"2015-03-15 00:00:00","CPU_Purchased_ghz":"10.00"},
    {"D":"2015-03-16 00:00:00","CPU_Purchased_ghz":"10.00"}
];

我希望它看起来像这样：

[
    ["D","CPU_Purchased_ghz"],
    [""2015-03-14 00:00:00",10.00],
    ["2015-03-16 00:00:00",10.00]
]

---

你知道如何修复/修改我的代码吗？

如果这解决了你的问题，你能接受它作为答案吗？谢谢

while($row = odbc_fetch_array($rs)) {
    $data[$i] = array(
        $row['D'],
        $row['CPU_Purchased_ghz']
    );
    $i++; 
}