How do I SUM DISTINCT Rows?

Question

I\'m struggling with a query where I need to SUM DISTINCT Rows. There has to be a way to do this... but I\'m lost.

Here\'s what I\'ve got:

SELECT D         


        

Answer 1

An easy answer is use "group by". Group by has the same effect with the same fields as distinct, but allows you to use aggregate functions. You can add a "Having" clause after the group by to filter what records you would like to see.

Answer 2

Use GROUP BY along with the SUM() and COUNT() aggregates.

SELECT count(*) as totalRows, Zipcodes.CountyID,
   sum(us_co_est2005_allData.PopEstimate2005) as SumPopEstimate2005, 
   sum(us_co_est2005_allData.EstimatesBase2000) as SumEstimatesBase2000,
  users_link_territory.userID

FROM
  Zipcodes Inner Join Users_link_territory ON zipcodes.CountyID = 
  Users_link_territory.CountyID Inner Join
  us_co_est2005_alldata ON zipcodes.FIPS = us_co_est2005_alldata.State AND zipcodes.code = us_co_est2005_alldata.County

WHERE (users_link_territory.userid = 4)

GROUP BY  Zipcodes.CountyID,users_link_territory.userID

Depending on your db server, this will be more efficient than doing a sub-select.

Answer 3

If you just want an overall figure for it try

select sum(PopEstimate2005), sum(EstimatesBase2000)
from(
    SELECT  Distinct
        Zipcodes.CountyID, 
        us_co_est2005_allData.PopEstimate2005, 
        us_co_est2005_allData.EstimatesBase2000, 
        users_link_territory.userID 
    FROM 
        Zipcodes Inner Join 
        Users_link_territory ON zipcodes.CountyID = Users_link_territory.CountyID Inner Join 
        us_co_est2005_alldata ON zipcodes.FIPS = us_co_est2005_alldata.State AND zipcodes.code = us_co_est2005_alldata.County 
    WHERE 
        (users_link_territory.userid = 4)
) as foo