mysqli last insert id - php

Question

I would like to associate the image with firstname, lastname...how can I retrieve the last rowand use it to insert to the other table? I tried $image = $mysqli->insert_id; then binding but it doesn't work. Can someone help me out?
$image = $mysqli->insert_id;//this should come from table2
$stmt = $mysqli->prepare("
insert into table1 (username, firstname, lastname, image)
select ?,?,?,image from table2 t2 where username = ? and t2.id = ?
");
$stmt->bind_param('sssss', $username, $fname, $lname, $username, $image);
$stmt->execute();

Answer 1

mysqli::$insert_id -- mysqli_insert_id — Returns the auto generated id used in the last query, Example:
$mysqli = new mysqli("localhost", "my_user", "my_password", "world");
/* check connection */
if (mysqli_connect_errno()) {
printf("Connect failed: %s\n", mysqli_connect_error());
exit();
}
$mysqli->query("CREATE TABLE myCity LIKE City");
$query = "INSERT INTO myCity VALUES (NULL, 'Stuttgart', 'DEU', 'Stuttgart', 617000)";
$mysqli->query($query);
printf ("New Record has id %d.\n", $mysqli->insert_id);
/* drop table */
$mysqli->query("DROP TABLE myCity");
/* close connection */
$mysqli->close();
output
New Record has id 1.
Reference
PHP mysqli_insert_id: http://www.php.net/manual/en/mysqli.insert-id.php

Answer 2

First of All you need to create auto_increment field in you ID
Then You can used
$last_id = mysqli_insert_id($conn);

Answer 3

after I get the last row from table2 I would like to insert it to table1. That is all I need
Go on:
insert into table 1 with simple regular insert query
get last insert id
insert into table 2 with simple regular insert query
As simple as that