Thread: Using distinct with sum()

Hello,

I've trying to sum up distinct columns.  But it's summing them prior to
the distinct taking effect.

--
CREATE TABLE t1 (
    id        integer,
    value1        integer,
    value2        integer,
    value3        integer
    );

INSERT INTO t1 (id,value1,value2,value3) VALUES (1,100,300,null);
INSERT INTO t1 (id,value1,value2,value3) VALUES (1,100,300,1);
INSERT INTO t1 (id,value1,value2,value3) VALUES (1,100,300,2);
INSERT INTO t1 (id,value1,value2,value3) VALUES (2,200,400,3);
INSERT INTO t1 (id,value1,value2,value3) VALUES (3,400,500,4);

SELECT DISTINCT id,value2 - value1 AS total FROM t1;

  id | total
----+-------
   1 |   200
   2 |   200
   3 |   100
--

Now what I'd like to do count(id) and sum(total)

--
SELECT DISTINCT count(id),sum(value2 - value1) AS total FROM t1;

  count | total
-------+-------
      5 |   900
--

I can get count() working how like by doing count(DISTINCT id) but how
do I do get a query to produce the following output (count/sum
post-distinct):

  count | total
-------+-------
      3 |   500

Thank you in advance,
- A Gilmore

hi

maybe not elegant, but it works:

SELECT count(id) as id,
               sum(total) as total
from (SELECT DISTINCT count(id),sum(value2 - value1) AS total FROM t1)
as t2;

Yours,
Christoph

A Gilmore schrieb:
> Hello,
>
> I've trying to sum up distinct columns.  But it's summing them prior
> to the distinct taking effect.
>
> --
> CREATE TABLE t1 (
>     id        integer,
>     value1        integer,
>     value2        integer,
>     value3        integer
>     );
>
> INSERT INTO t1 (id,value1,value2,value3) VALUES (1,100,300,null);
> INSERT INTO t1 (id,value1,value2,value3) VALUES (1,100,300,1);
> INSERT INTO t1 (id,value1,value2,value3) VALUES (1,100,300,2);
> INSERT INTO t1 (id,value1,value2,value3) VALUES (2,200,400,3);
> INSERT INTO t1 (id,value1,value2,value3) VALUES (3,400,500,4);
>
> SELECT DISTINCT id,value2 - value1 AS total FROM t1;
>
>  id | total
> ----+-------
>   1 |   200
>   2 |   200
>   3 |   100
> --
>
> Now what I'd like to do count(id) and sum(total)
>
> --
> SELECT DISTINCT count(id),sum(value2 - value1) AS total FROM t1;
>
>  count | total
> -------+-------
>      5 |   900
> --
>
> I can get count() working how like by doing count(DISTINCT id) but how
> do I do get a query to produce the following output (count/sum
> post-distinct):
>
>  count | total
> -------+-------
>      3 |   500
>
> Thank you in advance,
> - A Gilmore
>
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