致命錯誤PHP

Question

我正在做一個管理面板，我正在做一個添加用戶的表單。我下面的代碼：

 <form class="form-horizontal"> 
<fieldset> 

<!-- Form Name --> 
<legend>Add user</legend> 

<!-- Prepended text--> 
<div class="form-group"> 
    <label class="col-md-4 control-label" for="newuser">Username</label> 
    <div class="col-md-4"> 
    <div class="input-group"> 
     <span class="input-group-addon">@</span> 
     <input id="newuser" name="newuser" class="form-control" placeholder="Username" type="text" required=""> 
    </div> 
    <p class="help-block">Put the new users username here</p> 
    </div> 
</div> 

<!-- Password input--> 
<div class="form-group"> 
    <label class="col-md-4 control-label" for="userpw">New user password</label> 
    <div class="col-md-4"> 
    <input id="userpw" name="userpw" type="password" placeholder="Password" class="form-control input-md" required=""> 
    <span class="help-block">Enter new user's password here!</span> 
    </div> 
</div> 

<!-- Select Basic --> 
<div class="form-group"> 
    <label class="col-md-4 control-label" for="permissions">Choose permissions</label> 
    <div class="col-md-4"> 
    <select id="permissions" name="permissions" class="form-control"> 
     <option value="1">System administrator</option> 
     <option value="2">Editor</option> 
     <option value="3">Developer</option> 
     <option value="4">Normal user</option> 
    </select> 
    </div> 
</div> 

<!-- Button --> 
<div class="form-group"> 
    <label class="col-md-4 control-label" for="btn_send">Send request to server</label> 
    <div class="col-md-4"> 
    <button id="btn_send" name="btn_send" class="btn btn-primary">Send it!</button> 
    </div> 
</div> 

</fieldset> 
</form> 
<?php 
$newuser = $_GET['newuser']; 
$userpw = $_GET['userpw']; 
$permission = $_GET['permissions']; 


if(isset($newuser and $userpw and $permission) { 
    $sql = "INSERT INTO users(username,userpw,permission)VALUES('$newuser', '$userpw','$permission')"; 

    mysql_query($sql); 
} 
else { 
echo "error";} 

，我也得到：

致命錯誤：無法表達式的結果使用isset（）函數（您可以改用「空==表達！」）在C：\ xampp \ htdocs \ lumino \ usermanagement.php on line 95

我無法修復它，玩這個5小時。 它做$ _ GET方法，所以我得到的網址，如：

mysite.com/usermanagement.php?newuser=Berkay & userpw = 18042003個&權限= 3 & btn_send =

Answer 1

使用isset，你可以」噸有多個項目裏面：

if(isset($newuser and $userpw and $permission) { 

需求，成爲：

if(isset($newuser) && isset($userpw) && isset($permission)) { 

或者：

if(isset($newuser, $userpw, $permission)) { 

Answer 2

你只是錯過)和一組,：

if(isset($newuser, $userpw, $permission)) { 
    $sql = "INSERT INTO users(username,userpw,permission)VALUES('$newuser', '$userpw','$permission')"; 

    mysql_query($sql); 
}