+----------+    +-------------+
! panel    !    ! assembly    !
+----------+    +-------------+
! panel_id !    ! assembly_id !
! ...      !    ! panel_id    !
!----------!    ! ...         !
                +-------------+

+-------------+-------+-------+-------+-------+-------+-------+---
! assembly_id ! cost1 ! cost2 ! cost3 ! cost4 ! cost5 ! cost6 ! ...
+-------------+-------+-------+-------+-------+-------+-------+---
! 1           ! 100   ! 0     ! 20    ! 300   ! 0     ! 0     ! ...
! 3           ! 200   ! 0     ! 40    ! 100   ! 0     ! 0     ! ...
! 6           ! 300   ! 0     ! 600   ! 200   ! 0     ! 0     ! ...
! 12          ! 400   ! 0     ! 700   ! 300   ! 0     ! 0     ! ...

CREATE STORED PROCEDURE sp_panel_breakdown(p_panel_id INT)
BEGIN
    -- create temporary table
    DROP TABLE IF EXISTS breakdown;
    CREATE TEMPORARY TABLE breakdown(breakdown_id INT NOT NULL AUTO_INCREMENT, assembly_id INT, cost1 DECIMAL(10,2), cost2 DECIMAL(10,2), ..., cost10 DECIMAL(10,2), PRIMARY KEY (breakdown_id));

    -- insert data into temporary table
    SELECT sf_assembly_breakdown(assembly_id) as dummy
        FROM assembly
        WHERE panel_id=p_panel_id;

    -- return temporary table
    SELECT * FROM breakdown;
END

CREATE STORED FUNCTION sf_assembly_breakdown(p_assembly_id INT) RETURNS INT
BEGIN
    -- do cost calculations
    ...

    -- insert calculated costs as a new row in temporary table
    INSERT INTO breakdown SELECT null, p_assembly_id, cost1, cost2, ..., cost10;

    -- return dummy value
    RETURN null;
END