php mysql database connection error - php

Question

I have the following php code that gets user login details from a html form:
$con=mysqli_connect("host","user","pass","db");
// Check connection
if (mysqli_connect_errno())
{
echo "Failed to connect to MySQL: " . mysqli_connect_error();
}
$query = "select username from users where user='$_POST[username]' limit1";
$result = mysql_query($query);
echo result;
But when I run it, i seem to be getting these errors:
Warning: mysql_query() [function.mysql-query]: Can't connect to local
MySQL server through socket '/directory omitted' (2) in
/directory omitted on line 10
Warning: mysql_query() [function.mysql-query]: A link to the server
could not be established in
/directory omitted on line 10
Can anyone please help out? thanks very much!

Answer 1

You have mixed mysqli with mysql so there's a lot of typos
Code should be:
$con = mysqli_connect("host","user","pass","db");
// Check connection
if (mysqli_connect_errno()) {
echo "Failed to connect to MySQL: " . mysqli_connect_error();
}
$u = $_POST['username'];
$sql = "SELECT username FROM users WHERE user='$u' LIMIT 1";
$query = mysqli_query($con, $sql);
if ($row = mysqli_fetch_assoc($query)) {
echo $row['username'];
}
Hope it worked.
Or if you need all rows printed it should be:
while ($row = mysqli_fetch_assoc($query)) {
echo $row['username'];
}

Answer 2

$query = "select username from users where user='$_POST[username]' limit1";
$result = mysql_query($query);
These lines should be Like the following
$query = "SELECT username FROM users WHERE user='".$_POST['username']."' LIMIT 0,1";
$result = mysqli_query($con,$query);
print_r(mysqli_fetch_array($result));