Question

我有一段威士忌数据库，销售价格在一段时间内。在我的数据库中，我有Name，Price Url和Id。

我有很多同名的威士忌，但促销价格不同。目前，当有人进行搜索时，会将他们带到显示他们搜索过的产品的搜索结果页面。

我想要做的是当有人点击链接查看完整的详细信息时，我希望能够显示该名称下所有威士忌的平均价格，但我很难看到。它的ressult.php我遇到的问题是我得到的回应是£。我似乎已经失去了名字和网址被回应并没有得到名称url_img或平均价格（我试图计算。但我的重点是得到平均价格显示。

的search.php

$stmt = $conn->prepare("SELECT * FROM test_db WHERE name LIKE :name ORDER BY name ASC"); // Use = instead of LIKE for full matching
$stmt->bindParam(':name', $search);  
$stmt->execute();
$count = $stmt->rowCount(); // Added to count no. of results returned

if ($count >= 1) { // Only displays results if $count is 1 or more

    echo "<div class='results_found'>";
    echo $count; 
    echo " results found<br>";
    echo "</div>";

while ($row = $stmt->fetch(PDO::FETCH_ASSOC)) {

echo "<div class='results'>";
        echo "<div class='result_name'>";
                echo "<b>Whisky Name:</b><br>";
                echo "<a href='details1.php?id={$row['lot_id']}' >{$row['name']}</a>";
        echo "</div>";
        echo "</div>";
} 

} else {
      echo " Sorry no records were found";
}

?>

**results.php**

    <?php

    $page='details';
    include('header.php');
    include ('navbar.php'); 
    include ('connect.php');

    if (isset($_GET['id'])) {
    $sql = "SELECT name , AVG(price) , url_img , price FROM test_db JOIN (SELECT name, AVG(price) as avprice FROM test_db GROUP BY name) avcalc USING (name)
    WHERE lot_id = :id";
    $stmt = $conn->prepare($sql);
$stmt->execute( [ 'id' => $_GET['id'] ] );
$row = $stmt->fetch();
echo $row['name'];
echo '<br>';
echo '£';
echo $row['price'];
echo '<br>';
echo "<img src='".$row ['url_img']."' /><br />";
echo $row['avg'];

}

    ?>

Answer 1

我认为你正在寻找这个：

SELECT `name`, AVG(price) as avg_price FROM `whisky` GROUP BY `name`

原始表数据：

此问题的结果：

如果您只需要一个价格，则可以针对 WHERE name = whisky

扩展此查询

Avg现在位于：$ row [＆＃39; avg_price＆＃39;]

Answer 2

您已经应用了加入查询，但您获得了AVG（价格），而不是 avgprice ，它出现在第一个表 test_db 中。您需要创建另一个 test_db 的别名。改变这一行

$sql = "SELECT name , AVG(price) , url_img , avprice FROM test_db JOIN (SELECT name, AVG(price) as avprice FROM test_db GROUP BY name) avcalc USING (name) WHERE lot_id = :id";

到此

$sql = "SELECT name , avcalc.avgprice , url_img , avprice FROM test_db JOIN (SELECT name, AVG(price) as avprice FROM test_db GROUP BY name) avcalc USING (name) WHERE lot_id = :id";

Answer 3

知道了，

if (isset($_GET['id'])) {
$sql = "SELECT name 
        , price
        , url_img 
        , avprice 
        FROM test_db 
        JOIN (
            SELECT name
            , AVG(price) as avprice 
            FROM test_db 
            GROUP BY name
            ) avcalc USING (name)
        WHERE lot_id = :id";
$stmt = $conn->prepare($sql);
$stmt->execute( [ 'id' => $_GET['id'] ] );
$row = $stmt->fetch();
echo "{$row['name']}<br>
    &pound;{$row['price']}<br>
    <img src='{$row['url_img']}'/><br>
    {$row['avprice']}";

从所选产品中选择平均价格并回显

3 个答案: