MYSQL z PHP5 na PHP7 nefunguje vkládání dat do databáze

$connection=mysqli_connect('$db_server', '$db_login', '$db_heslo');
mysqli_select_db("$db_jmeno");
$vysledek2 = mysqli_query($connection, "SELECT * FROM `$db_jmeno`.`$tbpro` WHERE kod = '$kod'");
$zaznam2 = mysqli_fetch_array($vysledek2, MYSQL_BOTH);
if ($zaznam2!=""){
$sql = "UPDATE $tbpro SET datum = '$datum', cas ='$cas', test = '$test', ot1 = '$ot1', ot2 ='$ot2', ot3='$ot3', ot4 = '$ot4', ot5 ='$ot5', ot6='$ot6', vysledek='$vysledek' WHERE kod = '$kod';";
mysqli_query($connection, $sql) or die("Chyba databaze - vložení dat - UPDATE.");
}else{
$sql = "INSERT INTO $tbpro SET kod = '$kod', datum = '$datum', cas = '$cas', test = '$test', ot1 = '$ot1', ot2 = '$ot2', ot3 = '$ot3', ot4 = '$ot4', ot5 = '$ot5', ot6 = '$ot6', vysledek='$vysledek';";
mysqli_query($connection, $sql) or die("Chyba databaze - vložení dat - INSERT.");
}

mysqli_select_db($connection, "$db_jmeno");

$connection=mysqli_connect('$db_server', '$db_login', '$db_heslo', '$db_jmeno');