通过PHP检查mysql表中是否存在用户名? [英] Check if username exists in mysql table via php?

问题描述

我试图弄清楚如何使我的注册php代码检查注册人的用户名是否已被使用，如果已注册，请不要注册它，告诉用户它已被使用. 这是我的整个注册处理文件.

I am trying to figure out how to have my register php code check whether or not the registee's username is already taken, and if it is, don't register it, tell the user that it's taken. Here's my entire register processing file.

<?php
$con=mysqli_connect("localhost","root","","users");
// Check connection
if (mysqli_connect_errno())
  {
  echo "Failed to connect to MySQL: " . mysqli_connect_error();
  }

$hpassword = hash( 'sha512', $_POST['password'] );
$eusername = mysqli_real_escape_string( $con, $_POST['username'] );
$eemail = mysqli_real_escape_string( $con, $_POST['email'] );
$fusername = str_replace(' ', '', $eusername);

$sql="INSERT INTO users (username, password, email)
VALUES
('$fusername','$hpassword','$eemail')";

if (!mysqli_query($con,$sql))
  {
  die('Error: ' . mysqli_error($con));
  }
mysqli_close($con);
?> 

推荐答案

$sql=mysql_query("SELECT FROM users (username, password, email) WHERE username=$fusername");
 if(mysql_num_rows($sql)>=1)
   {
    echo"name already exists";
   }
 else
    {
   //insert query goes here
    }

您可以从数据库中检查用户是否存在，然后粘贴代码

you can check from database whether user exists and then paste the code

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