PHP MySQL数据库连接错误

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));