PHP: find out the primary key of the just-inserted row data - php

Question

I'm trying to find out the id value which is the primary key of the table. In order to do so, I implemented a code like this.
public function addNewPost($userName, $content) {
// insert post information into the data.
$query = "INSERT INTO posts(uploader, content, uploaded_at) VALUES('$userName', '$content', NOW())";
$result = mysqli_query($this->db->connect(), $query);
$id = mysqli_insert_id($this->db->connect());
if ($result) {
// get the row data with the found primary key
$query_get_row_data = "SELECT * FROM posts WHERE id = '$id'";
$result_row_data = mysqli_query($this->db->connect(), $query_get_row_data);
return mysql_fetch_array($result_row_data);
} else {
return false;
}
}
Here I tried to get the id by running thhe $id = mysqli_insert_id($this->db->connect()); command, but it doesn't seem to work.
Any solutions?

Answer 1

You need to use a connection variable not a function call. A second call to connect() is returning a new connection.
$connection = $this->db->connect();
$result = mysqli_query($connection, $query);
$id = mysqli_insert_id($connection);
Or if you keep a variable in the db class which makes sense:
$result = mysqli_query($this->db->connection, $query);
$id = mysqli_insert_id($this->db->connection);

Answer 2

Save the connection
public function addNewPost($userName, $content) {
// insert post information into the data.
$query = "INSERT INTO posts(uploader, content, uploaded_at) VALUES('$userName', '$content', NOW())";
$con = $this->db->connect();
$result = mysqli_query($con, $query);
$id = mysqli_insert_id($con);
if ($result) {
// get the row data with the found primary key
$query_get_row_data = "SELECT * FROM posts WHERE id = '$id'";
$result_row_data = mysqli_query($this->db->connect(), $query_get_row_data);
return mysql_fetch_array($result_row_data);
} else {
return false;
}
}