I want to calculate sum from different table

Question

I want to calculate sum from different table. I'm New in PHP Please help me. Below i have attached screenshot, All the values comes from database.

<table class="table table-bordered" id="sum_table">
    <tr>
    <th style="background-color: #ff7f7f">Items:</th>
    <td style="background-color: #44768e">Amount</td>
    </tr>
        <th>Total</th>
<td><?php

$qry = mysqli_query ("
SELECT sum(Price) 
  FROM rice 
 WHERE date BETWEEN DATE_FORMAT(NOW() - INTERVAL 1 MONTH, '%Y-%m-01') AND DATE_FORMAT(NOW() ,'%Y-%m-01')
");
$row2 = mysqli_fetch_assoc($qry);
echo $row2['total'];


$qry = mysqli_query ("
SELECT sum(Price) 
  FROM egg 
 WHERE date BETWEEN DATE_FORMAT(NOW() - INTERVAL 1 MONTH, '%Y-%m-01') AND DATE_FORMAT(NOW() 
,'%Y-%m-01')
");
$row = mysqli_fetch_assoc($qry);
echo $row['total'];

$total = $row['total'] + $row2['total'];
echo $total;

?></td>
</tr>

</table>

Answer 1

You have 2 issues in your code:

Issue 1: mysqli_query() required 2 parameters, you are not using your connection variable in your mysqli_query()

Issue 2: if you want to sum like $row['total'] + $row2['total']; that then you must need to define alias in your query something like:

SELECT SUM(column) as total FROM tablename

Its better to use PHP error reporting on local environment, this will help you to check actual errors instead of blank pages.

Example:

ini_set('display_errors', 1);
ini_set('display_startup_errors', 1);
error_reporting(E_ALL);

Edit:

This is good point highlighted by @spencer7593 in comment, you are directly calculating both values, for suppose if your query not returns anything then you will get new error.