　　(B) to achieve a white registering operation, as shown in the following code (implemented on a log)

Second, to achieve registration

1. Layout:

lable {display: inline-flex; width: 30px; height: 30px;} // achieve automatic alignment of the input box, otherwise uneven.

2. Ideas

a) the authentication data reasonableness:

　　　 1. When the form is submitted (onsubmit attribute), by JS of document.getElementById ( "id"). Value to obtain account passwords

　　　 2. str.trim () == '' confirmation is not empty, str.indexOf ( "") determines whether the user name without the spaces

　　　 Analyzing two pwd1 == pwd2 same password, pwd.length <8 determines the length of the password is not less than 8

　　 3. above are not met then the alert, and returns false, denying the author

b) verify that the user name is repeated:

　　　　By the name attribute in a form to post background regist_judge), using $ _POST [ 'name'] to obtain the value of submitting the form, by $ mysqli_result = db-> query ( "sql statement Find") information is stored in database tables db, in while in = $ mysqli_result (fetch_array (MYSQL_ASSOC)) acquiring a first message (3-> 2-> 1) by $ row, with $ row [ 'user'] == $ username determines whether the user name already exists in the database

　　　　i) Repeat:

　　　　　　header () points to the login screen, and by $ _SESSION [ 'flag'] registration failure message is transmitted, the registration interface to alert (user login failure information);

　　　　ii) will not be repeated:

　　　　 if ($ judge = $ db-> query ($ sql insert statement) === true) // echo generating a tag inserted successfully used to jump to the login screen

c) repeating process Username:

　　　　After the background returns a registration interface, using if (isset ($ _ SESSION [ 'flag'])) determines whether there In Flag, exists then the user name repeated, echo JS in Alert (); and using unset ($ _ SESSISON [ 'flag ']) destroy it

Code

regist.php // registration interface

<?php
    session_start();

    if(isset($_SESSION['flag']) ){
        echo "<script type='text/javascript'>alert('用户名已存在')</script>";
        unset($_SESSION['flag']);
    }

?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>注册</title>
    <style type="text/css">
        label{width:80px;display:inline-flex;height:30px;}
        .registall{border:10x solid pink;width:600px;height:300px;margin:200px auto;border:2px solid pink;box-shadow:0 0 5px 0 #aaa; border-radius:30px;}
        .regist .submit{position:relative;left:115px;top:10px;width:75px;height:27px;}
        .regist {width:300px;margin:20px auto;}
        .registall .title{font-size:23px;color:pink;text-align:center;margin-bottom:20px;margin-top:38px;}
    </style>
    <script type="text/javascript">
    
        function judge(){
            var username = document.getElementById("username").value;
            var password1 = document.getElementById ( "password1"). value;
             var password2 = document.getElementById ( "password2"). value;
             / * Analyzing data is valid * / 
            IF . (username == '' || username TRIM () = = '') alert ( "user name can not be empty" );
             the else  IF (username.indexOf ( "") = - 1) Alert (! "user name can not contain spaces" );
             the else  IF (password1 == '' | | password2 == '' || password1. the TRIM () == '' || password2. the TRIM () == '' ) 
                Alert ( "password can not be blank" );
            else if(password1 !=password2) 
                Alert ( "two passwords must match" );
             the else  IF (password1.length <. 8) Alert ( "not less than the length of the password. 8" );
             the else  return  to true ;
             return  to false ; 
        }
     </ Script> 
</ head> 
    
<body> 
    <div class = "registall"> 
        <div class = "title"> registration interface </ div> 
        <form class = "REGIST" Action = "regist_judge.php" Method = "POST" the onsubmit = "return Judge ( ); "> 
            <label> username: </ label>          
            <input id = "username" name = "username" type = "text" placeholder = " Enter your user name" /> </ br>
            <label> Password: </ label>           
            <INPUT ID = "password1" name = "password1" type = "password" placeholder = "password length exceeds. 6" /> </ br> 
            <label> Confirm Password: </ label >      
            <the iNPUT the above mentioned id = "password2" name = "password2" of the type = "password" placeholder = "Please enter your password again" /> </ br> 
            <the iNPUT of the type = "the Submit" value = "registered" class = "the Submit" / > 
        </ form> 
     </ div> 

</ body> 
</ HTML>

regist_judge.php // login interface judgment

<?php
    session_start();
    include("connect.php");
    $username = $_POST["username"];
    $password1 = $_POST["password1"];
    $password2 = $_POST["password2"];
    $sql_judge = "select username from user_msg where username='{$username}'";
    $mysqli_result = $db->query($sql_judge);
    while($row = $mysqli_result->fetch_array (MYSQL_ASSOC)) { 
　　　　 / * is determined whether there is the user name * /
         IF ( $ Row [ 'username'] == $ username ) {
             $ _SESSION [ 'In Flag'] =. 1 ; 
            header ( "LOCATION: regist.php" ) ;
             Exit (); 
        } 
    } 
    $ SQL = "iNSERT user_msg (username, password) values ( '{ $ username }', '{ $ password1 }')" ; 
　　// into the database
     IF ( $ Judge = $ DB -> Query ( $ SQL ) === to true ) {
         echo "<br/><div style='text-align:center;'>注册成功<br/><br/> <strong>
        <a href='login.php' style='text-decoration:none;font-size:20px;color:pink;'> 登录</a></strong></div>";
    }
            
?>

Registration can log message board (2) - to achieve registration