Sum of values of a column in PHP

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I am trying to add the results of an SQL column, but it does not return anything in my function.

Here you have a function that returns all the data in the table registros and the function that should add up the values of the column valor.

<thead>
    <tr>
        <th>ID</th>
        <th>Valor</th>
    </tr>
</thead>
<tbody>
<?php 
    include_once('conexao.php');

    $sql = "SELECT * FROM registros";
    $sql2 = "SELECT SUM(valor) as total FROM registros";

    $resultado = mysqli_query($con, $sql);
    $resultado2 = mysqli_query($con, $sql2);

    while($dados = mysqli_fetch_array($resultado))
        {
    ?>
        <tr>
            <td><?php echo $dados['id']?></td>
            <td><?php echo $dados['valor']?></td>
        </tr>
<?php 
    }
    while($dados2 = mysqli_fetch_array($resultado2))
    {
    ?>
    <div class="col-md-12 float-left mt-3"><?php echo $dados2['total'] ?>   </div>
    <?php 
    }
?>

The first while correctly returns all table rows with id and valor. The second while who calls the $sql2 returns nothing.

I’d like to understand what I’ve done wrong.

php sql

  • Where is the closure of tbody and of table? By code, you are placing a div in the middle of the table. Regarding the sum, I tested it here and it worked normally. What is the type of data in the column valor?

1 answer

0

You can also do as follows:

<thead>
    <tr>
        <th>ID</th>
        <th>Valor</th>
    </tr>
</thead>
<tbody>
<?php 
include_once('conexao.php');
$sql = mysqli_query($con, "SELECT * FROM registros");

$total = 0;
while($dados = mysqli_fetch_array($sql)){
    $total += $dados['valor'];
?>
    <tr>
        <td><?php echo $dados['id']?></td>
        <td><?php echo $dados['valor']?></td>
    </tr>
<?php } ?>
<div class="col-md-12 float-left mt-3"><?php echo $total; ?>   </div>

This way we assign $total, for a sum within your loop, with this you will get the result of the total, note that before the loop we set it to zero.

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