如何将来自不同表但相同数据库mysqli php的2列相乘[关闭]

Question

<?php

$con = mysqli_connect("localhost", "root", "", "zoo");

if (mysqli_connect_error()) {
    echo "Failed to connect" . mysqli_connect_error();
}

$sel = "Select * from animal where quantity";

$result = mysqli_query($con, $sel);

while ($row = mysqli_fetch_array($result)) {

    echo "<tr>";
    echo"<td>" . $row['quantity'] . "</td>";
}
$qsel = "Select * from price where bill";
$result = mysqli_query($con, $qsel);
while ($row = mysqli_fetch_array($result)) {

    echo "<tr>";
    echo "<td>" . $row['bill'] . "</td>";
}
?>

如何将来自不同表但相同数据库 mysqli php 的 2 列相乘

Answer 1

$con = mysqli_connect("localhost", "root", "", "zoo");

if (mysqli_connect_error()) {
    echo "Failed to connect" . mysqli_connect_error();
}

$sel = "select (quantity* bill) as total from animal inner join price on animal.id=price.animal_id group by price.animal_id";
$result = mysqli_query($con, $sel);
while ($row = mysqli_fetch_array($result)) {

    echo "<tr>";
    echo"<td>" . $row['total'] . "</td>";
}

在复制和粘贴之前检查您的表关系列名称并相应更新。

Answer 2

试试这个，它会给你整个结果，而无需在 php 中进行操作。

select (quantity* bill) as total from animal inner join price on animal.id=price.animal_id group by price.animal_id;