Only display values of latest available event type

Question

SQL Fiddle:

CREATE TABLE Purchasing (
    Event_Type VARCHAR(255),
    Campaign VARCHAR(255),
    Quantity_Offer VARCHAR(255),
    Quantity_         


        

Answer 1

Use this for your query.

this is based you first make your offer, then comes tghe order and at last comes the received, when 1 of them in that order is empty, then 1 prior must be the current state.

SELECT
Campaign,
IF(QReceived IS NOT NULL, "Received",
   IF(QOrder IS NOT NULL, "Order",
      IF(QOffer IS NOT NULL, "Offer", NULL))) Event_Type,
IF(QReceived IS NOT NULL, QReceived,
   IF(QOrder IS NOT NULL, QOrder,
      IF(QOffer IS NOT NULL, QOffer, NULL))) qty
      FROM
(SELECT 
 Campaign,
SUM(Quantity_Received) QReceived,

   SUM(Quantity_Order) QOrder,
   SUM(Quantity_Offer) QOffer

FROm Purchasing
GROUP BY Campaign) t1

Which gives you foolowing result

Campaign    Event_Type  qty
C001        Received    310
C002        Received    190
C003        Order       450
C004        Order       630
C005        Offer       400
C006        Offer       300

http://www.sqlfiddle.com/#!9/2b9394/34