Cannot get data using mysql_query

Question

I have a problem in using mysql_query. I always get the result zero even my query is correct because I tried executing my query directly in the database and I got a result. Please see my code below :

<?php
$username = $_POST['user'];
$password = $_POST['pass'];

$username = stripcslashes($username);
$password = stripcslashes($password);
$username = mysql_real_escape_string($username);
$password = mysql_real_escape_string($password);


mysql_connect("localhost","root","");
mysql_select_db("login");

$query = sprintf("select * from users where username='$username' and password='$password'");
$result = mysql_query($query);

$row = mysql_fetch_array($result);

if($row['username'] == $username && $row['password'] == $password)
{
    echo "Login Successful! Welcome".$row['username'];
}
else{
    echo "Login Failed";
}

?>

Answer 1

您使用sprintf，但未提供变量占位符，并且使用单引号而不是双引号，因此不会解析变量。

Answer 2

Help yourself by adding some debugging.

After this...

$result = mysql_query($query);

Add this...

if (!$result) {
    die('Invalid query: ' . mysql_error());
}

Save and re-run the code.

Let us know if you get a mysql_error().

Answer 3

1. You must check is query ended successfully.

   if(!$result) { print mysql_error(); die(); }

2. mysql is outdated. Use PDO