从数据库计算总行数

Question

I am trying to calculate the total amount of all the prices I get from my database but I can't figure it out. Its a bill from a restaurant.

$parameters = array(':tafelnummer'=>$tafelnummer);

$sth = $pdo->prepare("select * from bestellingen WHERE Tafelnummer = '$tafelnummer'");
$sth->execute();




while($row = $sth->fetch())
{
    
    
    echo "<tr> ";
        echo "<td>" . $row['Name'] . "</td>"; 
        echo "<td>" . $row['Soort'] . "</td>";
        echo "<td> " . $row['Price'] . "</td>";
    echo "</tr> "; 
    

}

The price wil give a result for each dish which I need a total amount for

Answer 1

SELECT SUM(Price) AS Totalamount 
FROM bestellingen 
WHERE Tafelnummer = '$tafelnummer' 

use this query than get the Totalamount.

Answer 2

Rather than going back to the database, you can keep an accumulator and then add a TOTAL line to the bill.

Also I have attempted to fix your SQL Injection issue.

$sth = $pdo->prepare("select * from bestellingen WHERE Tafelnummer = :tn");
$sth->execute([':tn' => $tafelnummer]);

$tot = 0;

while($row = $sth->fetch()) {
        
    echo "<tr> ";
        echo "<td>" . $row['Name'] . "</td>"; 
        echo "<td>" . $row['Soort'] . "</td>";
        echo "<td> " . $row['Price'] . "</td>";
    echo "</tr> "; 

    $tot += (float)$row['Price'];
}

echo "<tr> ";
    echo "<td>&nbsp;</td><td>TOTAL</td><td>$tot</td>";
echo "</tr> ";

Answer 3

Just use a variable $total and add each price into it in the while loop.

$total=0;

while($row = $sth->fetch())
{
    $total+=(int)$row["Price"];
    echo "<tr> ";
      echo "<td>" . $row['Name'] . "</td>"; 
      echo "<td>" . $row['Soort'] . "</td>";
      echo "<td> " . $row['Price'] . "</td>";
    echo "</tr> "; 
}

Make sure your Price value is always integer. It is not necessary to typecast to (int).