Updating mysql database table with variable from php calculation - php

Question

I am making an addition using php and I want to update the output to a column from my database.
This is what I have:
$api = "https://blockchain.info/ticker";
$json = file_get_contents($api);
$data = json_decode($json, TRUE);
$rate = $data["USD"]["sell"];
$symbol = $data["USD"]["symbol"];
$query = $db->query("SELECT * FROM bit_buysell WHERE status='1' ORDER BY id");
if($query->num_rows>0) {
while($row = $query->fetch_assoc()) {
echo ''.$row[name].' '.$row[currency].''.$row[price].'';
}
}
echo "<br><center> <b>1 BTC = " . $rate . $symbol . "</b></center></div>";
?></li>
<?php
$query = $db->query("SELECT * FROM bit_buysell WHERE id='1' ORDER BY id");
if($query->num_rows>0) {
while($row = $query->fetch_assoc()) {
echo ''.$row[prce].'';
$first_number = $rate ;
$second_number = $row[price];
$sum_totalbuy = $first_number * $second_number;
print ($sum_totalbuy);
}
}
I have been able to successfully add the the bitcoin price ticker and my custom value which returns the result I want in the print ($sum_totalbuy);
I want to therefore update my database by changing a table which automatically reference the $sum_totalbuy
Here is what i have done -
mysql_query("UPDATE bit_rates SET id='38' WHERE rate_from='$sum_totalsell'");
it didn't work and I have this too which I don't know how to go about it
Here is the code that manually update it via my dashboard, because I have to enter rate from and rate to:
<div class="card-body">
<form action="" method="POST">
<div class="form-group">
<label>List with exchange rates</label>
<select class="form-control" name="rid">
<?php
$query = $db->query("SELECT * FROM bit_rates ORDER BY id");
if($query->num_rows>0) {
while($row = $query->fetch_assoc()) {
echo '<option value="'.$row[id].'">'.gatewayinfo($row[gateway_from],"name").' '.gatewayinfo($row[gateway_from],"currency").' ('.$row[rate_from].' '.gatewayinfo($row[gateway_from],"currency").') = '.gatewayinfo($row[gateway_to],"name").' '.gatewayinfo($row[gateway_to],"currency").' ('.$row[rate_to].' '.gatewayinfo($row[gateway_to],"currency").')</option>';
}
} else {
echo '<option>No gateways</option>';
}
?>
</select>
</div>
<div class="form-group">
<label>New exchange rate</label>
<div class="input-group">
<span class="input-group-addon" id="basic-addon1">Rate from</span>
<input type="text" class="form-control" name="rate_from" placeholder="1" aria-describedby="basic-addon1">
<span class="input-group-addon" id="basic-addon1">= Rate to</span>
<input type="text" class="form-control" name="rate_to" placeholder="0.95" aria-describedby="basic-addon1">
</div>
</div>
<button type="submit" class="btn btn-primary" name="btn_update_rate"><i class="fa fa-check"></i> Update</button>
</form>
Please help me fix it.$sum_totalbuy
I need to store the print ($sum_totalbuy); to be updated in rate_from I will handle rate_to $sum_totalbuy

Answer 1

i have finally gotten it to work and this is what i did.
I had to do a total reconnect to my database then did the query update.
<?php
$server = "host";
$user = "user";
$pass = "pass";
$db = "db";
// Create connection
$conn = mysqli_connect($server, $user, $pass, $db);
// Check connection
if (!$conn) {
die("Could not connect: " . mysqli_connect_error());
}
$sql = "UPDATE bit_rates SET rate_from='$sum_totalsell' WHERE id=38";
if (mysqli_query($conn, $sql)) {
echo "Sell Rate Update successful.";
}
$sql = "UPDATE bit_rates SET rate_to='$sum_totalbuy' WHERE id=37";
if (mysqli_query($conn, $sql)) {
echo "Buy Rate Update successful.";
}
else {
echo "Could not update: " . mysqli_error($conn);
}
mysqli_close($conn);
?>
That directly updates the table in my sql
Thanks everyone for the time
i found the help here https://www.bitdegree.org/learn/mysql-update-syntax/