PHP调用MYSQL语句并获取输出

Question

EDIT-非常感谢大家的帮助。在继续学习的过程中，我现在正在根据上面学到的内容发表不同的声明，但没有任何结果。工作台将查询语句显示为良好，并将结果显示为"；2〃；

<?php
$servername = "localhost";
$username = "xxx";
$password = "xxx";
$dbname = "xxx";
// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);
// Check connection
if ($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，并让它输出值。以下是我尝试过的。有人能告诉我我做错了什么吗？

<?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_managern"
. "n"
. "WHERE `booking_date` >= DATE(NOW()) - INTERVAL 7 DAY  n"
. "ORDER BY `Time`  ASC";
?>

Answer 1

您的代码不完整，您必须建立到数据库的连接，然后执行查询以获得输出。你可以在这里和这里找到一些好的例子

Answer 2

您需要执行查询并获取如下结果：

<?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_managern"
. "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();
?>