如何使用php对数据库中的列求和

Question

我正在尝试对列名“总计”求和。我想按 id 显示总排序。如果用户 A 登录，他可以在他的帐户中看到总预订量。我不断收到错误：“注意：Array 中的数组到字符串的转换。”有人能帮我吗？我想以输入形式回显总数。这是我的 php 代码：<?php    include ('connect.php');    $sql = "SELECT * FROM penjaga WHERE p_username = '".$_SESSION['username']."'";    $result = mysqli_query($conn,$sql);    $row = mysqli_fetch_assoc($result);    $id = $row['p_id'];    $sql2 = "SELECT SUM(total) as total FROM sitter_kucing WHERE sitter_fk = '$id'";    $row2 = mysql_fetch_array($sql);    $sum = $row['total'];?>

Answer 1

试试这个，

$sql2 = "SELECT SUM(total) as total FROM sitter_kucing WHERE sitter_fk = '$id'";

$result2 = mysql_query($sql2) or die(mysql_error());

$row2 = mysql_fetch_array($result2) or die(mysql_error());

$sum = $row['total'];

Answer 2

我知道了！谢谢这是我的代码

这是代码：

  <?php

   include ('connect.php');

   $sql8 = "SELECT * FROM penjaga WHERE p_username = '".$_SESSION['username']."'";

   $result8 = mysqli_query($conn,$sql8);

   $row8 = mysqli_fetch_assoc($result8);

   $id = $row8['p_id'];

   $sql9 = "SELECT SUM(total) as total FROM sitter_kucing WHERE sitter_fk = '$id'";

   $result9 = mysqli_query($conn,$sql9);

   $row9 = mysqli_fetch_array($result9);

   $sum = $row9['total'];

   ?>