Question

$ query =选择并无法打印查询结果。当我删除if（$ results == true）时，网页将运行。但是一旦放置了if语句，它将不再加载。

数据库图访问https://www2.cs.uregina.ca/~webstesa/a2/2019-10-erd.png

<?php
session_start();
//If nobody is logged in, display login and signup page.
if(isset($_SESSION["email"]))
    {
        $email = $_SESSION["email"];
    ?>
    <!DOCTYPE html>
    ...
    </nav>
    </br>
    <?php 
        $db = new mysqli("localhost", "xxxxxxxx", "xxxxxxxx", "xxxxxxxx");
    if ($db->connect_error)
        {
            die ("Connection failed: " . $db->connect_error);
        }
    else
        {
            $query = "SELECT question.question, question.create_dt
            FROM question INNER JOIN User 
            ON question.user_ID = User.user_Id
            WHERE User email = '".$_SESSION["email"]."'";
            $result = $db->query($query);
            $num_row = $result -> num_row;
            echo $num_row; 
            if ($result == true)
            {
                if ($row = $result -> fetch_assoc())
                {
                    print (.$row["question"]);
                    print ("Date Asked: " .$row["create_dt"] "<br>");
                    print ("<div class = qb");
                    print (<"<br>");
                }
            }
        }
$db->close();
?>  
</body>
</html>
<?php }
else {
    echo "<a href='Login.php'>LogIn</a>";
    }
?>

我正在尝试介绍用户提出的5个最新问题。我已设置页面，以便用户登录，如果不是，则将他们重定向到登录页面。一切正常，但我似乎无法加载问题。

Answer 1

您只需要检查if ($result)，就不需要任何条件。试试这个代码

if ($result)
    {
        if ($row = $result -> fetch_assoc())
            {
                print (.$row["question"]);
                print ("Date Asked: " .$row["create_dt"] "<br>");
                print ("<div class = 'qb'");
                print (<"<br>");
            }
    }

在某些情况下，您不能使用the GLOBAL variable，而应将其存储在变量中并在查询中使用。 尝试此查询

$email = $_SESSION["email"];
$query = "SELECT question.question, question.create_dt
        FROM question INNER JOIN User 
        ON question.user_ID = User.user_Id
        WHERE User email = '$email'";
        $result = $db->query($query);

引用> https://stackoverflow.com/a/2060359/9246297

Answer 2

我认为您的查询字符串不正确，请尝试以下查询字符串-

$query = "SELECT question.question, question.create_dt
FROM question INNER JOIN User 
ON question.user_ID = User.user_Id
WHERE User email = ".$_SESSION['email'];

$result = $db->query($query);
$num_row = $result -> num_row;
echo $num_row; 
if ($result){
    if ($row = $result -> fetch_assoc()){
        print (.$row["question"]);
        print ("Date Asked: " .$row["create_dt"] "<br>");
        print ("<div class = qb");
        print (<"<br>");
    }
}

我的php没有显示数据库查询的结果

2 个答案: