php - 如何通过 jquery keyup 检查数据库中是否存在用户名

Question

嗨，我正在创建一个包含用户名密码等的表单。我使用 jquery 来验证该表单，我想检查该用户名是否已存在于 mysql 数据库中。如果存在，则不应提交表单。

这是迄今为止我的代码:

<form id="register" name="register" action="somewhere.php" method="post" >
   <label for ="Username"> Username </label><br>
     <input type="text" class="register-control" id="Username" name="Username" autocomplete="off"  placeholder="Enter Username"> <br>
     <div class="username_avail_result" id="username_avail_result"></div><br>
   <label for ="Password"> Password </label><br>
     <input type="password" class="register-control" id="password" name="password" placeholder="Enter Password" ><br><br>
   <label for ="Confirm-Password"> Confirm Password </label><br>
     <input type="password" class="register-control" id="Confirm_Password" name="Confirm_Password" placeholder="Confirm Password" ><br>
   <label for="email" > Email </label><br>
     <input type ="email" class="register-control" id="email" name="email" placeholder="Enter Valid Email"><br><br>
 <button type="submit" >Submit</button>

 </form>

jquery 是:

<script type="text/javascript" src="jquery-1.9.1.js"></script>
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.5.2/jquery.min.js"></script>
<script type="text/javascript" src="http://ajax.aspnetcdn.com/ajax/jquery.validate/1.8/jquery.validate.min.js"></script>
<script type="text/javascript">
$(document).ready(function(){
$('#Username').keyup(function(){ // Keyup function for check the user action in input
    var Username = $(this).val(); // Get the username textbox using $(this) or you can use directly $('#username')
    var UsernameAvailResult = $('#username_avail_result'); // Get the ID of the result where we gonna display the results
    if(Username.length > 2) { // check if greater than 2 (minimum 3)
        UsernameAvailResult.html('Loading..'); // Preloader, use can use loading animation here
        var UrlToPass = 'action=username_availability&username='+Username;
        $.ajax({ // Send the username val to another checker.php using Ajax in POST menthod
        type : 'POST',
        data : UrlToPass,
        url  : 'checker.php',
        success: function(responseText){ // Get the result and asign to each cases
            if(responseText == 0){
                UsernameAvailResult.html('<span class="success">Number available</span>');
            }
            else if(responseText > 0){
                UsernameAvailResult.html('<span class="error">Number already taken</span>');
            }
            else{
                alert('Problem with sql query');
            }
        }
        });
    }
});



$("#register").validate({


errorElement: 'div',
rules:{
"Username":{
  required: true,     
  minlength:5
},
"password":{
  required:true,
  minlength:5
},
"Confirm_Password":{
  required:true,
  equalTo: "#password"
},
"email":{
  required:true,  
}
},
messages: {
Username:{
             required: "Please provide a username",
            minlength: "Your Username must be at least 5 characters long"
},
 password: {
            required: "Please provide a password",
            minlength: "Your password must be at least 5 characters long"
            },
 Confirm_Password: {
            required: "Please provide a confirm password",
            equalTo: "Please enter the same password as above"
            }
},
email:{
            required: "Please provide a valid email",
} 
 });  
});
</script>

两者都工作得很好，我的疑问是如何合并两者，而且如果用户名已被使用，则不应提交表单。

Answer 1

在您的 php 文件中运行查询，获取当前电子邮件地址(即“example@example.com”)和用户名(即“example”)的所有用户(如果有) rows 那么它存在，因此不要添加它，否则，添加它!

    $_GET['email'] = $email;
    $result = mysql_query("SELECT * FROM users WHERE email='$email'");
    if($result === FALSE) {
        die(mysql_error()); // TODO: better error handling
    }
    if(mysql_num_rows($result) >= 1) { 
        //show already registered
       //you can either return false or change the return string/array to "registered"
    } else { 
       mysql_query('INSERT INTO users ..............);
    }