php注册账号+判断用户是否存在

新建一个PHP文件，将html和PHP代码放进去即可

html代码

<form name="" action="" method="post">
账号： <input class="input" type="text" name="number" placeholder="账号"></br>
密码：<input class="input" type="password" name="password" placeholder="密码"></br>
<input type="submit" name="submit" value="注册">
</form>

php代码

<meta charset = 'UTF-8'>
<?php
$dbhost = 'localhost:3306';
$dbuser = 'root';
$dbpass = 'root';
$conn = mysqli_connect( $dbhost, $dbuser, $dbpass );
if ( ! $conn ) {
    die( '连接错误: ' . mysqli_error( $conn ) );
}
mysqli_query( $conn, 'set names utf8' );
mysqli_select_db( $conn, 'xsdl' );
if ( isset( $_POST['submit'] ) ) {
    $user = $_POST['number'];
    $pwd = $_POST['password'];
    if ( $user == '' || $pwd == '' )
    {
        echo"<script>alert('用户名或密码不能为空！');history.go(-1)</script>";
    } else {
        $sqll = "select*from xinxi where name = '$user'";
        $res = mysqli_query( $conn, $sqll );
        $pass = mysqli_fetch_row( $res );
        if ( $pass ) {
            echo"<script>alert('用户名已存在！');history.go(-1)</script>";
        } else {
            $sql = 'INSERT INTO xinxi '.
            '(name,mima ) '.
            'VALUES '.
            "('$user','$pwd')";
            $retval = mysqli_query( $conn, $sql );
            if ( ! $retval ) {
                die( '注册失败 ' . mysqli_error( $conn ) );
            }
            echo "<script>alert('注册成功！')</script>";
            echo ( "<script>window.location.href= 'enter.php'; </script>" );
            //跳转页面location里ddd.html这个页面
        }
    }
}
mysqli_close( $conn )
?>