php - 我想添加费用和余额记录并将其更新到其他列或同一余额列，但只有第一条记录受到影响

Question

<?php
require_once "config.php";

$sql = "SELECT * FROM charges";
$results = mysqli_query($link, $sql);
$row = mysqli_fetch_array($results);
$count = mysqli_num_rows($results);

for ($i=0; $i <=$count ; $i++) { 
    $id = $row['c_id'];
    $newBalance = $row['charge']+$row['balance'];
    $query = "UPDATE charges SET balance = $newBalance WHERE c_id = $id";
    mysqli_query($link, $query)
}

？>

这是我的 php 代码 下图是我的数据库表

database table

Answer 1

您的查询是:

UPDATE charges SET balance = balance + charge

对于 php 来说是:

$sql = "UPDATE charges SET balance = balance + charge";
$results = mysqli_query($link, $sql);