php - 检查数据库中是否存在用户名

Question

如果用户名存在，就很难阻止用户注册。这是我的代码：

include('../connection.php');
//get all the names and values that have been posted.
    $username = $_POST['username'];   
    //check if username exists
    $sql = "SELECT * FROM tbl_Freelancers WHERE User_Username = '".$username."'";
    $result = mysqli_query($con,$query);
    if(mysql_num_rows($result)>=1)
       {
        echo"name already exists";
       }
     else
        {  // excecute insert query 

我试过很多其他的东西来让它工作，但是由于某些原因我的代码不喜欢我……

Answer 1

将mysql_num_rows更改为mysqli_num_rows

if(mysqli_num_rows($result)>=1)//You are mixing the mysql and mysqli, change this line of code
           {
            echo"name already exists";
           }
         else
            {  //

在查询中使用bind param或对值进行适当转义。