Codeigniter MYSQL data minus date1 data from date2 - php

Question

This is my Codeigniter project, I've made a bookshop function that counts the amount of brought and sold for the book in each entry and minus the sold price and gives me the amount that I currently have for each book.
Type "0" = The amount that I received
Else it's the amount that I spent
What I want to do now is I want to fetch the total amount that I received between date1 and date2 which should look something like "get_book_amount" for date1 -(minus) "get_book_amount" from date2.
The equation is like this:
On Date1 total amount that I received is 100, on Date2 it's 300. So the total amount that increased during that time is "200" which is the number I want to get.
How can I achieve this?
public function bookshop($date1,$date2)
{
$total_books = 0;
$books = '';
$this->db->select("*");
$this->db->from('books_s');
$this->db->where(['books_s.type' => 'Fantasy']);
$this->db->where(['books_s.stock' => 'Yes']);
$query = $this->db->get();
if($query->num_rows() > 0)
{
$count_books = $query->result();
if($count_books != NULL)
{
foreach ($count_books as $single_book)
{
$getamount = $this->get_book_amount($single_book->id,$date1,$date2);
if($getamount > 0)
{
$amt = $getamount;
}
else
{
$amt = -($getamount);
}
$total_books = $total_books+$amt;
$books .= '<tr><td><h4>'.$single_book->name.'</h4></td>
<td style="text-align:right" ><h4>'.$amt.'</h4></td></tr>';
}
$books .= '<tr"><td ><h4><i>Total Current Assets</i></h4></td><td style="text-align:right;" ><h4><i>'.$total_books.'</i></h4></td></tr>';
}
}
}
//USED TO COUNT SINGLE BOOK AMOUNT
public function get_book_amount($warehouse_id,$date1,$date2)
{
$count_total_amount = 0;
$this->db->select("bookentry.id as transaction_id,bookentry.date,bookentry.naration,book_stock_entry.*");
$this->db->from('book_stock_entry');
$this->db->join('bookentry', 'bookentry.id = book_stock_entry.parent_id');
$this->db->where('book_stock_entry.warehouse', $warehouse_id);
$this->db->where('bookentry.date >=', $date1);
$this->db->where('bookentry.date <=', $date2);
$query = $this->db->get();
if ($query->num_rows() > 0)
{
$count_books = $query->result();
$count_total_amount = 0;
if($count_books != NULL)
{
foreach ($count_books as $single_book)
{
if($single_book->type == 0)
{
$count_total_amount = $count_total_amount + $single_book->getamount;
}
else
{
$count_total_amount = $count_total_amount - $single_book->getamount;
}
}
}
}
if($count_total_amount == 0)
{
$count_total_amount = NULL;
}
else
{
$count_total_amount = number_format($count_total_amount,'3','.','');
}
return $count_total_amount;
}

Answer 1

I think it's best if you do two separete querys and then calculate.
Create a Model Method call "get_book_amount_until_date"
First call the method with your date 1 and save it in a var.
Second call the method with your date 2 and save it in another var.
Now do:
Total = Results_date_2 - Results_date_1