Why wont this simpy "INSERT INTO" query work - php

Question

I´m creating a simple register and login system for a school project where you sign up through a form.
This is my code for the sign up process (without the bunch of tests´ that determine if fields were left empty etc.), this is just the query part.
Sorry about the variables containing Danish signs (ÆØÅ), and being in danish, but i have made a couple of tests where it didn´t matter if i used æøå or some other kind of letters.
I simply can´t understand why this little piece of code won´t work:
//I retrieve alot of variables from a form
$Fornavn = mysql_real_escape_string($_POST["Fornavn"]);
$Efternavn = mysql_real_escape_string($_POST["Efternavn"]);
$Koen = mysql_real_escape_string($_POST["Koen"]);
$Etnicitet = mysql_real_escape_string($_POST["Etnicitet"]);
$Brugernavn = mysql_real_escape_string($_POST["Brugernavn"]);
$Password = mysql_real_escape_string($_POST["Password"]);
$Mail = mysql_real_escape_string($_POST["Mail"]);
$Haarfarve = mysql_real_escape_string($_POST["Haarfarve"]);
$Oejenfarve = mysql_real_escape_string($_POST["Oejenfarve"]);
$Vaegt = mysql_real_escape_string($_POST["Vaegt"]);
$Hoejde = mysql_real_escape_string($_POST["Hoejde"]);
//The query
mysqli_query($con, "INSERT INTO bruger (Fornavn, Efternavn, Køn, Etnicitet, Brugernavn, Password, Mail, Hårfarve, Øjenfarve, Vaegt, Højde)
VALUES ('$Fornavn', '$Efternavn', '$Koen', '$Etnicitet', '$Brugernavn', '$Password', '$Mail', '$Haarfarve', '$Oejenfarve', '$Vaegt', '$Hoejde')");
echo $Fornavn;
Edit:
I know it doesn´t work since nothing appears in my mysql database after i run the code.
It just returns zero rows (i use phpmyadmin btw.) And i don´t really get any error messages or anything.
As suggested i have tried to use Mysqli_* for my variables instead:
//I retrieve alot of variables from a form
$Fornavn = mysqli_real_escape_string($con,$_POST["Fornavn"]);
$Efternavn = mysqli_real_escape_string($con,$_POST["Efternavn"]);
$Koen = mysqli_real_escape_string($con,$_POST["Koen"]);
$Etnicitet = mysqli_real_escape_string($con,$_POST["Etnicitet"]);
$Brugernavn = mysqli_real_escape_string($con,$_POST["Brugernavn"]);
$Password = mysqli_real_escape_string($con,$_POST["Password"]);
$Mail = mysqli_real_escape_string($con,$_POST["Mail"]);
$Haarfarve = mysqli_real_escape_string($con,$_POST["Haarfarve"]);
$Oejenfarve = mysqli_real_escape_string($con,$_POST["Oejenfarve"]);
$Vaegt = mysqli_real_escape_string($con,$_POST["Vaegt"]);
$Hoejde = mysqli_real_escape_string($con,$_POST["Hoejde"]);
//The query
mysqli_query($con, "INSERT INTO bruger (Fornavn, Efternavn, Køn, Etnicitet, Brugernavn, Password, Mail, Hårfarve, Øjenfarve, Vaegt, Højde)
VALUES ('$Fornavn', '$Efternavn', '$Koen', '$Etnicitet', '$Brugernavn', '$Password', '$Mail', '$Haarfarve', '$Oejenfarve', '$Vaegt', '$Hoejde')");
echo $Fornavn;
But it doesn´t work.
Everything is stored as "Varchar" in the database with collation "utf8_danish_ci".
Answer to comments:
#John #Jayaram I do not retrieve any error messages, or perhaps i don´t know where they go? Im really new to Mysql and PHP.
#Adunahay Vaegt and Højde are stored as Varchar in the table.
#Gordon The code for the connection is as follows:
//We check the connection
$con = mysqli_connect("localhost","Mads","","meat-market");
//If there is a fail.
if (mysqli_connect_errno())
{
echo "<h1> Det er vores fejl:</h1><br /><h2>Kunne ikke forbinde til Databasen:</h2><br /> " . mysqli_connect_error();
exit;
}
Altough im sure the table exist and the database does since i can see it in Phpmyadmin. The user Mads also has all of the necessary permissions.
#Raphaël I´m not aware if you can use special chars, but i have made a couple of tests before where i tried with special chars and it seemed to work fine.
#dboals I don´t know what you mean (i´m new to php), further explanation would be welcomed.

Answer 1

It's because you're using mysql_* for your POST variables and mysqli_* for your DB connection and in your query using $con as the first variable, which is mysqli_* syntax.
Change:
$Fornavn = mysql_real_escape_string($_POST["Fornavn"]);
to
$Fornavn = mysqli_real_escape_string($con,$_POST["Fornavn"]);
and do the same for the others.
Sidenote: Use all mysqli_* functions exclusively for your entire code --- mysqli_* and mysql_* functions do not mix together.. (which I recommend you use and with prepared statements, or PDO)
An example of preparing and binding for mysqli_ can be found HERE.

Answer 2

I found out what was wrong.
First off i needed to change mysql_* to mysqli_* in my variables.
But after that it still didn´t work.
Then i tried to change the letters "æ ø å" to something that wasn´t special letters in the database.
It didn´t seem to matter in the variable names tho.
So instead:
Æ = AE
Ø = OE
Å = AA
So apparently special characters are no go, eventough it seems to be a bit inconsistent since i have done it with special characters before... I don´t know if it is dependent of the collaction of the database...
But thanks to everyone!
EDIT!:
I´m using the UTF8_Danish_ci collation in my table and all the rows.
But after this i still had the problem that if i entered a special character in the form, it would show up as A| or something like that in the database.
I have fixed this by doing the following for each variable that comes from the form:
$Fornavn =utf8_decode($_POST["Fornavn"]);
$Fornavn = mysqli_real_escape_string($con,$Fornavn);
And add the following parameter to my FORM tag:
accept-charset="UTF-8"
Still haven´t been able to execute mysqli queries where the row names contains Æ Ø or Å.