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 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)

This gives me the 34 rows which provide distinct population numbers for each county belonging to userid4, but how would I get the SUM of PopEstimate2005 and EstimatesBase2000?

Something like (but this isn't a legal query):

SELECT DISTINCT Zipcodes.CountyID,
SUM(us_co_est2005_allData.PopEstimate2005) AS Population2005, 
SUM(us_co_est2005_allData.EstimatesBase2000) AS Population2000,
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 users_link_territory.userid

Of course, as soon as I add Zipcodes.CountyID to the end of the GroupBy, I'm back with my 34 rows again.

Thanks so much for any help.

Russell Schutte . . . . .

After getting the below help - in particular Robb's help - I was able to get what I really wanted - a total of each UserID's population details in a single query:

SELECT     SUM(POPESTIMATE2005) AS Expr1, SUM(ESTIMATESBASE2000) AS Expr2, UserID
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
    ) As FOO
GROUP BY UserID

Thanks everyone who contributed!

Russell Schutte

Answer 1

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 2

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 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