Question

我正在尝试检查是否有可用的地方来预订活动，并且我使用if语句来执行此操作。如果语句检查registeredPlaces是否小于可用位置的总数，并且是否有可用位置，则应该允许预订并插入到clientEvent并更新activityEvent表中的bookingPlaces。如果没有可用的地方，它应该回应完全预订。它总是回应它已经预订完毕。我不确定如何在一个问题中插入和更新。

<?php

session_start();
require("connection.php");

$con=mysqli_connect("$mysql_host","$mysql_user","$mysql_password","$mysql_database");

// Check connection
if (mysqli_connect_errno())
{
    echo "Failed to connect to MySQL: " . mysqli_connect_error();
}

$sql ="select bookedPlaces, noOfPlaces from activityEvent";
$result = mysqli_query($con,$sql);
$clientID=$_SESSION['clientID'];
$activityEventID =$_SESSION['activityEventID'];

while($row = $result->fetch_assoc())
{
    $booked =$row['bookedPlaces'];
    $noofPlaces = $row['noOfPlaces'];
}

if($booked < $noofPlaces)
{
    echo "You have booked ";
    $sql="Insert into clientEvent(clientID, activityEventID) Values('$clientID','$activityEventID')";

    $sql= "update activityEvent set AvailablePlaces  = ($available -1) where activityEventID = $activityEventID";
    echo "$sql";
}
else
{
    echo "Fully booked ";
}

if (!mysqli_query($con,$sql))
{
    die('Error: ' . mysqli_error($con));
}
?>

Answer 1

我给你一个选择：我认为scheduledPlaces和noOfPlaces的某些行是null，所以你必须比较它们。您可以创建一个这样的计数器函数：

function counter($row){
$mysqli = new mysqli("localhost", "root", "", "first");
$res = $mysqli->query("SELECT COUNT({$row}) FROM records WHERE {$row} !='' ");  // !=0 or !=[what's your no value]
$row = $res->fetch_row();
return $row[0];
}

现在你可以使用

if(counter('bookedPlaces') < counter('noOfPlacest') {

在此选项中，保持fetch_assoc查询不变。

Answer 2

看起来整个if-else块if($booked < $noofPlaces)超出了while循环。因此，if语句正在评估意外值。

更正的代码应如下所示。

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

    $booked = $row['bookedPlaces'];
    $noofPlaces = $row['noOfPlaces'];

    if ($booked < $noofPlaces) {
        echo "You have booked ";
        $sql = "Insert into clientEvent(clientID, activityEventID) Values('$clientID','$activityEventID')";
        $sql = "update activityEvent set AvailablePlaces  = ($available -1) where activityEventID = $activityEventID";
        echo "$sql";
    }
    else {
        echo "Fully booked ";
    }
}

PHP if语句检查可用的地方

2 个答案: