Question

I am trying to create a view as follows:

CREATE VIEW vw1 AS SELECT     
  Town
, case when (Spend > 0 and NbOrders > 0)
       then sum(Spend)/sum(NbOrders)
       else null
       end as AvgSpend
, case when (Margin > 0 and NbOrders > 0)
       then sum(Margin)/sum(NbOrders)
       else null
       end as AvgMargin
FROM Table
group by Town

But I get an error because the fields used in my ‘case when…’ statement aren’t included in an aggregate function.

I can’t use a ‘where’ clause because the average fields depend on different fields being >0 and I can’t see how I could make the case when work on an aggregated field?

Any ideas how I can achieve this – preferably in a single statement?

Answer 1

Updated… thanks to @Andriy M

SELECT town

,SUM(CASE WHEN Spend > 0 and NbOrders > 0 THEN Spend END)
/SUM(CASE WHEN Spend > 0 and NbOrders > 0 THEN NbOrders END)  As AvgSpend

,SUM(CASE WHEN Margin > 0 and NbOrders > 0 THEN Margin END)
/ SUM(CASE WHEN Margin > 0 and NbOrders > 0 THEN NbOrders END) As AvgMargin

FROM table
GROUP BY town