PHP登录错误-无论用户是否存在，它总是让我登录

Question

代码-不确定发生了什么请帮助：

$accountname = $_POST['logname'];
$password = $_POST['logpassword']; 
echo '<br>';

$logsql = mysqli_query("SELECT Name FROM practice.users WHERE Name = $accountname and Password = $password;");
if (mysqli_num_rows($logsql) < 0) {
     echo 'Account doesnt exist';
}
else {
    echo 'Welcome ' . $accountname;
}

Answer 1

//wITHOUT TAKING SECURITY INTO CONSIDERATION AND BEST PRACTICESS CONSIDER BELOW

$accountname = $_POST['logname'];
$password = $_POST['logpassword']; 
echo '<br>';//WHY THIS LINE BREAK
//$logsql = mysqli_query("SELECT Name FROM practice.users WHERE Name = $accountname and Password = $password;");

// ADD A CONNECTION BEFORE A THE QUERY SEPERATED BY A COMMA
// ADD SINGLE QUOTES ON '$accountname' AND '$password' VARIABLES
$logsql = mysqli_query($connection, "SELECT Name FROM practice.users WHERE Name = '$accountname' AND Password = '$password'");
if (mysqli_num_rows($logsql) < 0) {
     echo 'Account doesnt exist';
}
else {
    echo 'Welcome ' . $accountname;
}