Re: A 3 table join question

On Fri, Aug 16, 2019 at 12:30:33PM -0700, Ken Tanzer wrote:
> On Fri, Aug 16, 2019 at 7:24 AM rob stone <floriparob@gmail.com> wrote:
>
> > Hello,
> >
> > On Fri, 2019-08-16 at 07:39 -0400, stan wrote:
> > > What am I doing wrong here?
> > >
> >
> >
> > Your view assumes that all three "streams" contain all the proj_no's
> > whereas your test data for expense_report_cost_sum_view has no proj_no
> > = 764.
> >
> >
> Hi.  I'm probably missing something, but it seems simpler to either join
> with USING, or by COALESCEing the two ID fields in left part of the JOIN
> clause (COALESCE(t1.proj_no,t2.proj_no)=t3.proj_no).
>
> Cheers,
> Ken
>
> CREATE TEMP TABLE t1 (id int, t1_val TEXT);
> INSERT INTO t1 VALUES (2,'T1_2');
> INSERT INTO t1 VALUES (5,'T1_5');
> INSERT INTO t1 VALUES (7,'T1_7');
> INSERT INTO t1 VALUES (10,'T1_10');
>
> CREATE TEMP TABLE t2 (id int, t2_val TEXT);
> INSERT INTO t2 VALUES (3,'T2_3');
> INSERT INTO t2 VALUES (5,'T2_5');
> INSERT INTO t2 VALUES (6,'T2_6');
> INSERT INTO t2 VALUES (10,'T2_10');
>
> CREATE TEMP TABLE t3 (id int, t3_val TEXT);
> INSERT INTO t3 VALUES (4,'T3_4');
> INSERT INTO t3 VALUES (6,'T3_6');
> INSERT INTO t3 VALUES (7,'T3_7');
> INSERT INTO t3 VALUES (10,'T3_10');
>
> SELECT id,t1_val,t2_val,t3_val
> FROM
>     t1
>     FULL JOIN t2 USING (id)
>     FULL JOIN t3 USING (id)
> ;
>
> SELECT COALESCE(t1.id,t2.id,t3.id) AS id,t1_val,t2_val,t3_val
> FROM
>     t1
>     FULL JOIN t2 ON (t1.id=t2.id)
>     FULL JOIN t3 ON (COALESCE(t1.id,t2.id)=t3.id)
> ;
>
>  id | t1_val | t2_val | t3_val
> ----+--------+--------+--------
>   2 | T1_2   |        |
>   3 |        | T2_3   |
>   4 |        |        | T3_4
>   5 | T1_5   | T2_5   |
>   6 |        | T2_6   | T3_6
>   7 | T1_7   |        | T3_7
>  10 | T1_10  | T2_10  | T3_10
> (7 rows)
>
OK, I am clearly not understanding this yet.

Here is what I am trying:


select
        COALESCE(
                labor_cost_sum_view.proj_no ,
                material_cost_sum_view.proj_no ,
                expense_report_cost_sum_view.proj_no
        )
AS
        proj_no ,
        labor_cost_sum_view.labor_cost_sum ,
        material_cost_sum_view.mtrl_cost ,
        expense_report_cost_sum_view.burdened_cost ,
                coalesce( labor_cost_sum_view.labor_cost_sum, 0)
                +
                coalesce(material_cost_sum_view.mtrl_cost, 0)
                +
                coalesce(expense_report_cost_sum_view.burdened_cost, 0)
from
        labor_cost_sum_view
full join    material_cost_sum_view  on
        material_cost_sum_view.proj_no = labor_cost_sum_view.proj_no
full join    expense_report_cost_sum_view  on
        expense_report_cost_sum_view.proj_no = labor_cost_sum_view.proj_no
;


Having simplified things a bunch, and removing casts and aliases etc.

But here is what I am getting as a result set:

proj_no | labor_cost_sum | mtrl_cost | burdened_cost |    ?column?   
---------+----------------+-----------+---------------+----------------
      45 |  3133.17500000 | 5394.6800 |   2564.980000 | 11092.83500000
     764 |   810.75000000 | 7249.4800 |               | 8060.23000000
     789 |  7015.57500000 |           |               | 7015.57500000
        7456 |                | 4007.3000 |               | 4007.3000
          33 |                |           |    241.380000 | 241.380000
        7456 |                |           | 1747.110000   | 1747.110000
(6 row

Note that project number 7456 appears in 2 rows.

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