php - 计算 SQL 组中的行数

Question

我有一个脚本想要放在仪表板上。 SQL 工作并对项目进行分组，并正确显示在仪表板中。不过，我还希望显示数量。

因此，如果 SQL 正在分组，我如何计算它返回的行数，以便我可以将每行的数量回显到表中。这是我的代码。

<?php
    $servername = "localhost";
    $username = "root";
    $password = "root";
    $dbname = "dbname";
    $custid = $row['CustomerID'];
    // Create connection
    $conn = new mysqli($servername, $username, $password, $dbname);
    // Check connection
    if ($conn->connect_error) {
        die("Connection failed: " . $conn->connect_error);
    } 
    $sql1 = "SELECT * FROM stock 
            JOIN hardware ON stock.HardwareID = hardware.HardwareID
            WHERE stock.CustomerID = $custid GROUP BY stock.HardwareID";
    $result1 = $conn->query($sql1);
    if ($result1->num_rows > 0) {
        // output data of each row
        while($row1 = $result1->fetch_assoc()) {
            echo "<tr>";
            echo "<td>".$row1['Hardware']."</td>";
            echo "<td></td>";
            echo "</tr>";
        }
    }
?>

所以目标是获得行

echo "<td></td>";

其中有一个变量，用于显示分组的每行的数量。

Answer 1

您可以使用此查询，按查询分组必须选择并提供聚合，这里我提供了计数，如果您需要一些适当的列，您可以相应地更改它...

            <?php
                $servername = "localhost";
                $username = "root";
                $password = "root";
                $dbname = "dbname";

                $custid = $row['CustomerID'];

                // Create connection
                $conn = new mysqli($servername, $username, $password, $dbname);
                // Check connection
                if ($conn->connect_error) {
                    die("Connection failed: " . $conn->connect_error);
                } 
                $sql1 = "SELECT stock.Hardwareid, count(*) as CountHardware FROM stock 
                JOIN hardware ON stock.HardwareID = hardware.HardwareID
                WHERE stock.CustomerID = $custid GROUP BY stock.HardwareID";
                    $result1 = $conn->query($sql1);

                if ($result1->num_rows > 0) {
                    // output data of each row
                    while($row1 = $result1->fetch_assoc()) {
                        echo "<tr>";
                        echo "<td>".$row1['Hardware']."</td>";
                        echo "<td></td>";
                        echo "</tr>";
                    }
                }
            ?>