我有两个表，每个表的名称为shipping_infos和orders。我想从这两个表中得到多个列。这两个表共享一个相同的列，即user_id列。我一直在尝试这个代码，但是它仍然返回null。我该怎么写？
<?php
include ('classes/functions.php');
if(isset($_POST['user_id'])){
$user_id = $_POST['user_id'];
$check_receipt = "select
shipping_infos.shipping_name,shipping_infos.shipping_address,
shipping_infos.shipping_contact,shipping_infos.shipping_email,
orders.order_date,orders.trx_id,orders.tracking_num from
shipping_infos inner join orders on shipping_infos.user_id = orders.user_id
where user_id= '".$user_id."';";
$run_receipt_checking = mysqli_query($con, $check_receipt);
$result = array();
while($row = mysqli_fetch_array($run_receipt_checking)){
array_push($result,
array(
'shipping_name'=>$row[2],
'shipping_address'=>$row[3],
'shipping_contact'=>$row[4],
'shipping_email'=>$row[5],
'order_date'=>$row[8],
'trx_id'=>$row[1],
'tracking_num'=>$row[2],
));
}
echo json_encode(array("result"=>$result));
} ?>
尝试此查询：
$check_receipt = "select si.shipping_name,
si.shipping_address,
si.shipping_contact,
si.shipping_email,
o.order_date,
o.trx_id,
o.tracking_num
from shipping_infos si
inner join orders o
on si.user_id = o.user_id
where si.user_id='".$user_id."';";
此处更改：
array_push($result,
array(
'shipping_name'=>$row[0],
'shipping_address'=>$row[1],
'shipping_contact'=>$row[2],
'shipping_email'=>$row[3],
'order_date'=>$row[4],
'trx_id'=>$row[5],
'tracking_num'=>$row[6],
));