Question

我想在html中显示“Vendido -Pagado”（我的表中的2列）的结果但是下面的代码不起作用，任何线索为什么？

 <?php
    //connect to db
    include '../connect.php';

    $saldo = "SELECT Vendido-Pagado AS Saldo FROM Cooks WHERE Mail = '$email'";
    $resultsaldo = mysqli_query($conn, $saldo);

      if (mysqli_num_rows($resultsaldo) > 0) {
        // output data of each row
                while($row3 = mysqli_fetch_assoc($resultsaldo) {
                  echo  '<a class="w-nav-link navlink right" href="../misaldo.php">Saldo: '
  .$row3['Saldo']. "</a>";

                  }}          else { echo "There was an error fetching the total";}

    mysqli_close($conn);
    ?>

Answer 1

对于MYSQL查询中的SUM，您可以使用MYSQL SUM aggregate function

$saldo = "SELECT (SUM(Vendido) + SUM(Pagado)) AS Saldo FROM Cooks WHERE Mail = '$email'";

OR

我使用了$row3['col1']和$row3['col2']来展示如何总结两列，不要忘记更改列的名称

col1，col2。

while($row3 = mysqli_fetch_assoc($resultsaldo) {

echo "Sum of two columns : ".($row3['col1'] + $row3['col2']);

}

注意：如果您使用mysqli，最好使用mysqli prepared statements.

Answer 2

您可以直接使用sql查询。

更改此

SELECT Vendido-Pagado AS Saldo FROM Cooks WHERE Mail = '$email'

到

SELECT CONCAT( Vendido,  '-', Pagado ) AS Saldo FROM Cooks WHERE Mail = '$email'

Php Mysql在html中显示2列的总和

2 个答案: