Not able to pass array data - php

Question

I am trying to create an array in $data, but it is not happening. I am using this code to make a day wise sale chart.
$data = array();
for ($i = 0; $i <= 10; $i++) {
$billdate = date('d-m-Y', strtotime("-$i day"));
$sqlQuery = "select sum(amount),bill_date from msr_bills WHERE bill_date='$billdate' ";
$result = mysqli_query($con, $sqlQuery);
$fetchamount = mysqli_fetch_row($result);
$sum = $fetchamount[0];
$data = new \stdClass();
$data->bill_date = $billdate;
$data->amount = $sum;
$report_JSON = json_encode($data);
echo $report_JSON.",";
}

Answer 1

You can merge your loop into one query, and then iterate over the results instead:
$data = array();
$billdate = date('Y-m-d', strtotime('-10 day'));
$sqlQuery = "SELECT bill_date, SUM(amount) AS amount
FROM msr_bills
WHERE bill_date >= '$billdate'
GROUP BY bill_date";
$result = mysqli_query($sqlQuery);
if ($result) {
while ($row = mysqli_fetch_assoc($result)) {
$data[] = (object)$row;
}
$report_JSON = json_encode($data);
echo $report_JSON;
}
Note that your date format is not compatible with MySQL dates, which are stored in Y-m-d format, and I have changed that in the code. If your bill_date column is actually a text field stored in d-m-Y format, you will need to convert it in the query like so:
$sqlQuery = "SELECT bill_date, SUM(amount) AS amount
FROM msr_bills
WHERE STR_TO_DATE(bill_date, '%d-%m-%Y') >= '$billdate'
GROUP BY bill_date";
Note also that you can in fact do the computation of $billdate internal to your SQL query using date arithmetic:
$sqlQuery = "SELECT bill_date, SUM(amount) AS amount
FROM msr_bills
WHERE STR_TO_DATE(bill_date, '%d-%m-%Y') >= CURDATE() - INTERVAL 10 DAY
GROUP BY bill_date";
And if you are running MySQL 8.0+, you can do the entire operation in MySQL:
$sqlQuery = "SELECT JSON_ARRAYAGG(data) AS data
FROM (SELECT JSON_OBJECT('bill_date', bill_date, 'amount', SUM(amount)) AS data
FROM msr_bills
WHERE bill_date >= CURDATE() - INTERVAL 10 DAY
GROUP BY bill_date) d";
$result = mysqli_query($sqlQuery);
if ($result) {
$row = mysqli_fetch_assoc($result);
$report_JSON = $row['data'];
echo $report_JSON;
}
Demo on dbfiddle

Answer 2

Put your echo outside loop. remove code $report_JSON = json_encode($data);
$respnseArr = array();
{
.
.
.
$respnseArr[] = $data;
}
echo json_encode($respnseArr);