如何将数据从php推送到多维数组[关闭]

I have an array variable and it will be used in a json. This is my code:

$arr = array();

    $data=mysql_query("SELECT * FROM t_location WHERE loca_id = '$id' ")or die(mysql_error());
    while($a=mysql_fetch_array($data)){
           array_push(); //what should i do
    {

I want to push data from database to array like:

$arr= array(
    array(
        "id" => "1",
        "name" => "London",       
    )
);  

Can anyone help me?

$arr = array();

$data=mysql_query("SELECT * FROM t_location WHERE loca_id = '$id' ")or die(mysql_error());
while($a=mysql_fetch_array($data)){
       array_push($arr,$a);
{