使用codeigniter中的连接活动记录获取db字段的总和

Question

I have a table name products with all product details and another whs_products with quantity details of the products for each warehouse.

i want select id, code and name from products table and sum of quantity where products.id = whs_products.product_id

I am trying this

$this->db->select("id, code, name");
$this->db->from("products");
$this->db->join('whs_products', 'products.id = whs_products.product_id');
$this->db->select("quantity");

I getting the list products that exists in whs_products not the sum. Some products are listed twice as they have 2 entries in whs_products.

I want list all the products once only where no quantity I want put 0 in quantity and where its is more than 1 in whs_products I want display sum of all the quantity

Help will be much appreciated!

Table Structure

Products
id, code, name, unit, price

whs_products
id, product_id, warehouse_id, quantity

I have whs table too for warehouse id, name, address

---

I tried this Sir,

$this->db->select("products.id as productid, products.code, products.name, products.unit, products.cost, products.price,   sum(whs_products.quantity) as 'totalQuantity'")
->from('products')
->join('whs_products', 'whs_products.product_id=products.id', 'left')
->group_by("products.id");
$this->db->get();

Every thing is fine. But the total number of products are calculated wrongly. I think system add 1 to total products, each time gets quantity from whs_products. For some products quantity is 2 or 3 time depending on each warehouse.

Any solutions for this. I am very thankful for your support.

Answer 1

Please try out the following query and comment.

• SQLFIDDLE DEMO

Sample data:-

Products

PID     PNAME
1   j
2   k
3   m

whs_Products

WID     PID     QUANTITY
11  2   300
11  2   200
14  2   500
11  1   300
15  3   100
14  3   800

Query to get total by pid in whs_products

select pid, wid, sum(quantity) 
from whs_products
group by pid, wid
;

Results:

PID     WID     SUM(QUANTITY)
1       11      300
2       11      500
2       14      500
3       14      800
3       15      100

query using a variable to get user input for pid and by pid, wid

-- group by pid and wid
set @var:='2'
;
select a.pid, b.pname, a.wid, sum(a.quantity) 
from whs_products a
join products b
on b.pid = a.pid
where a.pid = @var
group by a.pid, wid
;

Results:

PID     PNAME   WID     SUM(A.QUANTITY)
2       k   11  500
2       k   14  500

final query to show quantity by user input pid only

Query:

-- by pid only    
set @var:='2'
;
select a.pid, b.pname, sum(a.quantity) 
from whs_products a
join products b
on b.pid = a.pid
where a.pid = @var
group by a.pid
;

Results:

PID     PNAME   SUM(A.QUANTITY)
2       k   1000

Since OP wants in CodeIgniter

Here is a headstart for you to try. At first I had the impression you already know the syntax of codeigniter and you are looking for SQL logic, so you could convert it into the desired format you need.

$this->db->select("a.pid, b.pname, count(a.quantity) as 'toalQuantity'");
$this->db->from('wsh_products a');
$this->db->join('products b', 'a.pid=b.pid', 'inner');
$this->db->group_by("a.pid"); 
$where = "a.pid = 2";
$this->db->get();
$query->results_array();

Or write a funciton :) :

function getQuantity($prodid = false)
{
  $this->db->select(a.pid, b.pname, count(a.quantity) as 'toalQuantity');
  $this->db->join('wsh_products a', 'a.pid=b.pid');
  if ($prodid !== false)
    $this->db->where('a.pid', $prodid);
  $query = $this->db->get('products b');

  if($query->result() == TRUE)
  {
    foreach($query->result_array() as $row)
    {
      $result[] = $row;
    }
    return $result;
  }
}

---

Edit as OP requested for LEFT JOIN in comments

• SQLFIDDLE

To show all products in Products table, do the following:

• In select show pid from Products table.

• Use from Products Left Join Whs_Products

• Group by pid from Products table