Sum results for multiple queries

Question

I'm quite new in PHP/MySQL and I need to sum resuts of multiple queries grouped.

For example, I have a table like this:

Toy   |  Material 1  | Qt Mat 1 | Material 2 | Qt Mat 2 | Material 3 | Qt Mat 3

House |     Wood     |    2 kg  |    Cloth   |   1 kg   |   Rubber   |   0.5 kg
Horse |     Wood     |    3 kg  |   Rubber   |   2 kg   |            |
Plane |    Plastic   |    1 kg  |   Steel    |   2 kg   |   Rubber   |   0.2 kg 
Doll  |     Cloth    |    2 kg  |            |          |            |
Car   |   Rubber     |    1 kg  |    Plastic |   2 kg   |            |

Let's suppose that I want to build a House , a Doll and a Car .
My shopping list would be:

Wood - 2 kg (House)
Cloth - 3 kg (1 for House, 2 for Doll)
Rubber - 1.5 kg (0.5 for House, 1 for Car)
Plastic - 2 kg (Car) 

How can I generate this using PHP and MySQL?

Answer 1

SELECT Material,SUM(Qty) as NetQty
FROM (
      SELECT  Material1 as Material, QtMat1 as Qty
      FROM tableName
      WHERE Toy IN ('House','Doll','Car')

      UNION ALL 

      SELECT  Material2, QtMat2
      FROM tableName
      WHERE Toy IN ('House','Doll','Car')

      UNION ALL 

      SELECT  Material3, QtMat3
      FROM tableName
      WHERE Toy IN ('House','Doll','Car')

    ) As qry

   GROUP BY qry.Material