Something wrong with data insert - php

Question

Good day,i am trying to insert data into mysql table using php its kinda working but i can't see data in phpmyadmin
<?php
$con=mysqli_connect('localhost','root','');
if(!$con)
{
echo("not connected");
}
if(!mysqli_select_db($con,'exam'))
{
echo 'db not selected';
}
$header = $_POST['header'];
$date = $_POST['date'];
$categ = $_POST['categ'];
$moder = $_POST['moder'];
$posttxt = $_POST['posttxt'];
$theme = $_POST['theme'];
$author = $_POST['author'];
$sql = "INSERT INTO postex (header,date,categ,moder,posttxt,theme,author) VALUES ('$header','$date','$categ','$moder','$posttxt','$theme','$author')";
if
(empty($header) || empty($date) || empty($categ) || empty($moder) || empty($posttxt) || empty($theme) || empty($author))
{
echo "<Br>feel the fields!!!";
}
else{
echo("<br>added,wait for redirect");
}
?>

Answer 1

Ok, before anymore wrong answers come up using mysql_, it's mysqli_query($con, $sql) that wasn't used to execute the query.
RTM http://php.net/manual/en/mysqli.query.php
and take care of that sql injection that you're leaving yourself open to, if/when you go live with this.
https://en.wikipedia.org/wiki/SQL_injection
with a prepared statement
https://en.wikipedia.org/wiki/Prepared_statement
while making sure the POST arrays do contain values (and the form uses a POST method with matching named inputs) and that there are no characters passing through that MySQL could complain about, for example: apostrophes.
Escape the data going in, in any respect.
Check for errors via PHP and the query:
http://php.net/manual/en/function.error-reporting.php
http://php.net/manual/en/mysqli.error.php
Nota:
You should first check if any of the fields are (not) empty, then execute the query.
I.e. and pseudo conditionals:
if(none empty and good to go){
// execute the query
}
else{
// do something else
}
Plus, if you're using your entire code inside the same file, being the form and php/mysql, then you should check if any of the POST arrays are set/not empty first. That will throw a few errors and give you undesired results.

Answer 2

<?php
function db(){
$servername = "servername";
$username = "username";
$password = "password";
$database = "database";
// Create connection
$conn = new mysqli($servername, $username, $password,$database);
$conn->query("SET CHARACTER SET utf8");
// Check connection
if ($conn->connect_error) {
die("Connection failed: " . $conn->connect_error);
return false;
}else{
return $conn;
}
}
$data=db();
$insert="INSERT INTO movies (bla1, bla2, bla3) VALUES (blavalue1, blavalue2, blavalue3)";
$dotaz=mysqli_query($data,$insert);
if($dotaz){
echo "OK";
}else{
echo "Wrong";
}
?>