PHP调用MYSQL语句并获取输出

Question

在继续学习的过程中，我现在正在根据上面学到的内容编写不同的语句，但它没有给出任何结果。Workbench 显示查询语句良好，结果显示为“2”<?php$servername = "localhost";$username = "xxx";$password = "xxx";$dbname = "xxx";// Create connection$conn = new mysqli($servername, $username, $password, $dbname);// Check connectionif ($conn->connect_error) {  die("Connection failed: " . $conn->connect_error);}  $sql = "SELECT SUM(`mattiscool`),booking_date FROM `wp_cbxrbooking_log_manager` WHERE `booking_date` = CURDATE() -1";$result = mysqli_query($sql);while ($row = mysqli_fetch_assoc($result)){    echo $row['total'];}mysqli_close($con);?>我试图通过 php 调用 MySQL 语句并输出值。以下是我尝试过的。有人可以帮助我了解我做错了什么吗？<?php$sql = "SELECT DAYNAME(wp_cbxrbooking_log_manager.`booking_date`) as \'weekday\',  \n"    . "              wp_cbxrbooking_log_manager.`party_size` as \'Party Size\',\n"    . "              wp_cbxrbooking_log_manager.`booking_time` as \'Time\',\n"    . "              wp_cbxrbooking_log_manager.`mattiscool` as \'# of Reservations\'\n"    . "FROM wp_cbxrbooking_log_manager\n"    . "\n"    . "WHERE `booking_date` >= DATE(NOW()) - INTERVAL 7 DAY  \n"    . "ORDER BY `Time`  ASC";?>

Answer 1

您的代码不完整，您必须建立与数据库的连接，然后执行查询才能获取输出。

Answer 2

您需要执行查询并获取结果，如下所示：

<?php

$servername = "localhost";

$username = "username";

$password = "password";

$dbname = "myDB";

// Create connection

$conn = new mysqli($servername, $username, $password, $dbname);

// Check connection

if ($conn->connect_error) {

  die("Connection failed: " . $conn->connect_error);

}

$sql = "SELECT DAYNAME(wp_cbxrbooking_log_manager.`booking_date`) as \'weekday\',  \n"

    . "              wp_cbxrbooking_log_manager.`party_size` as \'Party Size\',\n"

    . "              wp_cbxrbooking_log_manager.`booking_time` as \'Time\',\n"

    . "              wp_cbxrbooking_log_manager.`mattiscool` as \'# of Reservations\'\n"

    . "FROM wp_cbxrbooking_log_manager\n"

    . "\n"

    . "WHERE `booking_date` >= DATE(NOW()) - INTERVAL 7 DAY  \n"

    . "ORDER BY `Time`  ASC";

$result = $conn->query($sql);

if ($result->num_rows > 0) {

  // output data of each row

  while($row = $result->fetch_assoc()) {

    echo "id: " . $row["id"]. " - Name: " . $row["firstname"]. " " . $row["lastname"]. "<br>";

  }

} else {

  echo "0 results";

}

$conn->close();

?>