使用php更新MySql查询以更新用户配置文件

我试图通过覆盖MySql中的当前数据来更新用户配置文件。 它工作不正常，它说它呼应我的“名字不存在”

        <form action="user1.php" method="POST">
            <div>
            <p>First Name: <input type="text" name="firstname" id="firstname" value="<?=$firstname?>"></p>
            <p>Surname: <input type="text" name="surname" id="surname" value="<?=$surname?>"></p>   
            <p>Weight: <input type="text" name="weight" id="weight" value="<?=$weight?>"></p>
            <p>Height: <input type="text" name="height" id="height" value="<?=$height?>"></p>
            <p> <input type="submit" name="submit" id="submit" value="Update Description"></p>
            </div>
        </form>
    </body>

以下是我的php代码：

        <form action="user1.php" method="POST">
            <div>
            <p>First Name: <input type="text" name="firstname" id="firstname" value="<?=$firstname?>"></p>
            <p>Surname: <input type="text" name="surname" id="surname" value="<?=$surname?>"></p>   
            <p>Weight: <input type="text" name="weight" id="weight" value="<?=$weight?>"></p>
            <p>Height: <input type="text" name="height" id="height" value="<?=$height?>"></p>
            <p> <input type="submit" name="submit" id="submit" value="Update Description"></p>
            </div>
        </form>
    </body>

``````

<?php
// see if the form has been completed
session_start();
include_once("php_includes/check_login_status.php");
include_once("php_includes/db_conx.php");
// Initialize any variables that the page might echo
$u = "";
$firstname = "";
$surname = "";
$gender = "Male";
$country = "";
$weight = "";
$height = "";
$password = "";
$password2 = "";

if(isset($_GET["u"])){
    $u = preg_replace('#[^a-z0-9]#i', '', $_GET['u']);
} 

$sql = "SELECT * FROM users WHERE username='$u' AND activated='1' LIMIT 1";
$user_query = mysqli_query($db_conx, $sql);

// check if the user exists in the database
while ($row = mysqli_fetch_array($user_query, MYSQLI_ASSOC)) {
    $firstname = $row["firstname"];
    $surname = $row["surname"];
    $weight = $row["weight"];
    $height = $row["height"];
    $email = $row["email"];
    $gender = $row ["gender"];
    }
if (isset($_POST['submit'])){
    $firstname = $_POST['firstname'];
    $surname = $_POST['surname'];
    $weight = $_POST['weight'];
    $height = $_POST['height'];
    $email = $_POST['email'];
    $gender = $_POST['gender'];
mysql_connect ("localhost","root","pass123");   mysql_select_db('worldoi5_social');
    // check if that user exist 
    $exists = mysql_query ("SELECT * FROM users WHERE username='$u' ") or die ("query cant connect");   
    if (mysql_num_rows ($exists) != 0) {
    // update the description in the database       
        mysql_query("UPDATE users SET firstname='$firstname', surname='$surname', weight='$weight', height='$height' WHERE username='$u'") or die ("update could not be applied");
        echo "successful";
} else echo "the name does not exist";  
}
?>

        <form action="user1.php" method="POST">
            <div>
            <p>First Name: <input type="text" name="firstname" id="firstname" value="<?=$firstname?>"></p>
            <p>Surname: <input type="text" name="surname" id="surname" value="<?=$surname?>"></p>   
            <p>Weight: <input type="text" name="weight" id="weight" value="<?=$weight?>"></p>
            <p>Height: <input type="text" name="height" id="height" value="<?=$height?>"></p>
            <p> <input type="submit" name="submit" id="submit" value="Update Description"></p>
            </div>
        </form>
    </body>

---

我找到了答案：

        <form action="user1.php" method="POST">
            <div>
            <p>First Name: <input type="text" name="firstname" id="firstname" value="<?=$firstname?>"></p>
            <p>Surname: <input type="text" name="surname" id="surname" value="<?=$surname?>"></p>   
            <p>Weight: <input type="text" name="weight" id="weight" value="<?=$weight?>"></p>
            <p>Height: <input type="text" name="height" id="height" value="<?=$height?>"></p>
            <p> <input type="submit" name="submit" id="submit" value="Update Description"></p>
            </div>
        </form>
    </body>

从php代码行

        <form action="user1.php" method="POST">
            <div>
            <p>First Name: <input type="text" name="firstname" id="firstname" value="<?=$firstname?>"></p>
            <p>Surname: <input type="text" name="surname" id="surname" value="<?=$surname?>"></p>   
            <p>Weight: <input type="text" name="weight" id="weight" value="<?=$weight?>"></p>
            <p>Height: <input type="text" name="height" id="height" value="<?=$height?>"></p>
            <p> <input type="submit" name="submit" id="submit" value="Update Description"></p>
            </div>
        </form>
    </body>

$exists=mysql\u查询（“从用户名为“$u”的用户中选择*）

        <form action="user1.php" method="POST">
            <div>
            <p>First Name: <input type="text" name="firstname" id="firstname" value="<?=$firstname?>"></p>
            <p>Surname: <input type="text" name="surname" id="surname" value="<?=$surname?>"></p>   
            <p>Weight: <input type="text" name="weight" id="weight" value="<?=$weight?>"></p>
            <p>Height: <input type="text" name="height" id="height" value="<?=$height?>"></p>
            <p> <input type="submit" name="submit" id="submit" value="Update Description"></p>
            </div>
        </form>
    </body>

单引号和双引号都搞砸了，所以我不得不这样使用它

        <form action="user1.php" method="POST">
            <div>
            <p>First Name: <input type="text" name="firstname" id="firstname" value="<?=$firstname?>"></p>
            <p>Surname: <input type="text" name="surname" id="surname" value="<?=$surname?>"></p>   
            <p>Weight: <input type="text" name="weight" id="weight" value="<?=$weight?>"></p>
            <p>Height: <input type="text" name="height" id="height" value="<?=$height?>"></p>
            <p> <input type="submit" name="submit" id="submit" value="Update Description"></p>
            </div>
        </form>
    </body>

$exists=mysql\u查询（“从firstname='“$firstname.”的用户中选择*”

        <form action="user1.php" method="POST">
            <div>
            <p>First Name: <input type="text" name="firstname" id="firstname" value="<?=$firstname?>"></p>
            <p>Surname: <input type="text" name="surname" id="surname" value="<?=$surname?>"></p>   
            <p>Weight: <input type="text" name="weight" id="weight" value="<?=$weight?>"></p>
            <p>Height: <input type="text" name="height" id="height" value="<?=$height?>"></p>
            <p> <input type="submit" name="submit" id="submit" value="Update Description"></p>
            </div>
        </form>
    </body>

然后，它正确地阅读了它，我决定立即使用firstname作为选择性的，将
mysqli.*
与
mysql.*
混合，做数学运算
$mysqli.*
+
mysql.*
=不可以。我过去做的是回显mysql.*

查询的内容，然后复制并粘贴到mysql客户端。75%的情况下，仅仅看到原始查询就可以让您注意到一些错误。另外，我真的不知道您为什么要使用

session_start（）用于此。没有分配给任何人。@Fred ii我是新来的，我不知道他们之间有什么不同，也看不到
session_start（）问题在于如何响应mysql查询@evilpenguin
        <form action="user1.php" method="POST">
            <div>
            <p>First Name: <input type="text" name="firstname" id="firstname" value="<?=$firstname?>"></p>
            <p>Surname: <input type="text" name="surname" id="surname" value="<?=$surname?>"></p>   
            <p>Weight: <input type="text" name="weight" id="weight" value="<?=$weight?>"></p>
            <p>Height: <input type="text" name="height" id="height" value="<?=$height?>"></p>
            <p> <input type="submit" name="submit" id="submit" value="Update Description"></p>
            </div>
        </form>
    </body>