Fail to insert into database - php

Question

I'm trying to make it possible to add something to my guestbook through the website. But the problem is: I fail to insert into the database.
Using my WAMP server I can insert into it directly using the query down here.
I've tested the $name variables as well and they are properly filled in. I've switched $con and $sql. and I tried to format the query in different ways without{} with {}. But not even one option seems to work. The connection with my DBS works (I didn't include that part here). I tried mysql_query and mysqlI_query.
My WAMP server has php_mysqli enabled. And when I run this it doesn't give any errors.
Do you guys know what I'm doing wrong?
$con = mysqli_connect($host, $username, $password)or die("cannot connect");
mysqli_select_db($con, $db_name)or die("cannot select DB");
$datetime=date("y-m-d h:i:s"); //date time
$name= $_POST['name'];
$email= $_POST['email'];
$comment= $_POST['comment'];
$sql="INSERT INTO guestbook(name, email, comment, datetime) VALUES('{$name}','${email}','{$comment}','{$datetime}')";
mysql_query($sql,$con);
// link to view guestbook page
header('location:viewguestbook.php');

Answer 1

Please try this,And next time you must search mysqli prepared statements.
$mysqli = new mysqli("localhost", "my_user", "my_password", "world");
if ($mysqli->connect_errno) {
printf("Connect failed: %s\n", $mysqli->connect_error);
exit();
}
$mysqli->query("insert...");

Answer 2

here is the problem in this statement
mysql_query($sql,$con);
problem 1: you are using mysqli and in above statement your are querying mysql.
problem 2: $con(connection variable is must be the first parameter)
Write this statement as folloing. that will solve the problem
mysqli_query($con,$sql);

Answer 3

In your insert query you have ${email} instead of {$email} and change mysql_query to mysqli_query
below is the code that should work
$con = mysqli_connect($host, $username, $password)or die("cannot connect");
mysqli_select_db($con, $db_name)or die("cannot select DB");
$datetime=date("y-m-d h:i:s"); //date time
$name= $_POST['name'];
$email= $_POST['email'];
$comment= $_POST['comment'];
$sql="INSERT INTO guestbook(name, email, comment, datetime) VALUES('{$name}','{$email}','{$comment}','{$datetime}')";
mysqli_query($sql,$con);

Answer 4

I don't know what error do you get. You can do this:
mysqli_query($con, $query) or die(mysqli_error($con));