Mathematical Function

Question

I have Database inside it 3 tables: A, B, C

A : (Item , Qty, Loc); B: (Item , Qty,Loc); C:(Item,Loc1,Loc2,Loc3,Loc4.......,Loc16) ;

I need a function for au

Answer 1

I would propose you, better than creating Triggers that are much more difficult to follow-up, create a View that will provide the requested information. Be aware that I put part of the query, need to be write the same portion of code for fields from 3 to 15:

CREATE VIEW C_View
    AS 
SELECT  C.Item, 
        C.Loc1, 
        COALESCE((SELECT SUM(Qty) FROM A WHERE A.Item = C.Item AND A.Loc = C.Loc1), 0) -
        COALESCE((SELECT SUM(Qty) FROM B WHERE B.Item = C.Item AND B.Loc = C.Loc1), 0) 
        AS Qty1,
        C.Loc2, 
        COALESCE((SELECT SUM(Qty) FROM A WHERE A.Item = C.Item AND A.Loc = C.Loc2), 0) -
        COALESCE((SELECT SUM(Qty) FROM B WHERE B.Item = C.Item AND B.Loc = C.Loc2), 0) 
        AS Qty2,
        ...
        C.Loc16, 
        COALESCE((SELECT SUM(Qty) FROM A WHERE A.Item = C.Item AND A.Loc = C.Loc16), 0) -
        COALESCE((SELECT SUM(Qty) FROM B WHERE B.Item = C.Item AND B.Loc = C.Loc16), 0) 
        AS Qty16,
FROM C;