Re: A 3 table join question

Hello,

On Fri, 2019-08-16 at 07:39 -0400, stan wrote:
> First let me say a huge THANK YOU to all the helpful people that
> hanging out
> on this.
>
> I am changing from one type of work, going back to some database work
> for a
> project, as my old job was eliminated. I have made great progress on
> this,
> thanks to the time and effort of lots of folks from this list.
>
> Now, here is my latest stumbling block. I have three "data streams"
> that all
> contribute to the total costs of a project:
>
> * labor cost
> * material cost
> * expense report cost
>
> I have a view that summarizes the burdened cost from each of these 3
> streams, and i am trying to create a view that shows the total
> project cost.
>
> Here is the test data from each of the 3 streams:
>
> stan=> select * from labor_cost_sum_view ;
> proj_no | labor_bill_sum | labor_cost_sum
> ---------+----------------+----------------
> 45 | 10810.0000 | 3133.17500000
> 764 | 8712.0000 | 810.75000000
> 789 | 46335.5400 | 7015.57500000
> (3 rows)
>
> stan=> select * from material_cost_sum_view ;
> proj_no | mtrl_cost
> ---------+-----------
> 45 | 5394.6800
> 764 | 7249.4800
> 7456 | 4007.3000
> (3 rows)
>
> stan=> select * from expense_report_cost_sum_view ;
> proj_no | incured_sum | burdened_cost
> ---------+-------------+---------------
> 45 | 2564.98 | 2564.980000
> 7456 | 1747.11 | 1747.110000
> (2 rows)
>
> And here is the clause for creating the summary table that I
> presently have:
>
>
> DROP VIEW overall_cost_sum_view ;
>
> CREATE view overall_cost_sum_view as
> select
> material_cost_sum_view.proj_no as l_proj_vo ,
> labor_cost_sum_view.proj_no as m_proj_vo ,
> expense_report_cost_sum_view.proj_no as x_proj_vo ,
> cast (labor_cost_sum_view.labor_cost_sum as money) as
> l_burdened_cost,
> cast (material_cost_sum_view.mtrl_cost as money)as
> m_burdened_cost,
> cast (expense_report_cost_sum_view.burdened_cost as money)as
> x_burdened_cost ,
> cast (
> coalesce( labor_cost_sum_view.labor_cost_sum,
> 0)
> +
> coalesce(material_cost_sum_view.mtrl_cost, 0)
> +
> coalesce(expense_report_cost_sum_view.burdene
> d_cost, 0)
> as money) as ttl_cost
> 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
> ;
>
> Which results in the following:
>
> stan=> select * from overall_cost_sum_view ;
> -----------+-----------+-----------+-----------------+---------------
> --+-------- ---------+------------
> 45 | 45 | 45 | $3,133.18
> | $5,394.68 | $ 2,564.98 | $11,092.84
> 764 | 764 | | $810.75
> | $7,249.48 | | $8,060.23
> | 789 | | $7,015.58
> | | | $7,015.58
> 7456
> | | | | $4,007.30
> | | $4,007.30
> | | 7456
> | | | $ 1,747.11 | $1,747.11
> (5 rows)
>
>
> As you can see this statement seems to work correctly on the join of
> the
> labor and material costs, but fails when I add the expense report
> stream.
>
> 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.

How do you know which of the three "streams" contains all proj_no's?

Maybe you should consider the crosstab code so you end up with
something like this;-

proj_no | Labour | Material | Expenses

45 | 10810 | 5394 | 2564
764 | 8712 | 7249 | 0
789 | 46335 | 4007 | 1747