Coalesce() in outer join between views

Hi everyone.

I am trying to create a view that fills in missing values from a 
secondary source.  I am using PostgreSQL 8.0.3 on Fedora Linux Core 3.

I have two important views and two important tables.  Everything works 
find by itself but when I try to create an outer join between views 
(that hit the same table) coalesce is giving bad results.

The first view is day_source_pre:   View "reporting.day_source_pre"Column |       Type       | Modifiers
--------+------------------+-----------day    | date             |amount | double precision |source | text
|
View definition:
( SELECT acc_trans.transdate AS "day", sum(acc_trans.amount) AS amount, 
payment_types.id AS source  FROM acc_trans, payment_types WHERE (acc_trans.chart_id IN ( SELECT chart.id          FROM
chart        WHERE chart.accno ~~ '1300.%'::text)) AND acc_trans.source ~~ 
 
(('%source='::text || payment_types.id) || '%'::text) GROUP BY acc_trans.transdate, payment_types.id
UNIONSELECT acc_trans.transdate AS "day", sum(acc_trans.amount) AS amount, 
'over/under' AS source  FROM acc_trans WHERE (acc_trans.chart_id IN ( SELECT chart.id          FROM chart         WHERE
chart.accno~~ '1300.%'::text)) AND acc_trans.source ~~ 
 
'%Over/under%'::text GROUP BY acc_trans.transdate)
UNIONSELECT acc_trans.transdate AS "day", sum(acc_trans.amount) AS amount, 
'Reset' AS source  FROM acc_trans WHERE (acc_trans.chart_id IN ( SELECT chart.id          FROM chart         WHERE
chart.accno~~ '1300.%'::text)) AND acc_trans.source ~~ 
 
'%Reset%'::text GROUP BY acc_trans.transdate;
This works as expected by itself.

The second view is:   View "reporting.day_inc_source"Column |       Type       | Modifiers
--------+------------------+-----------day    | date             |sum    | double precision |source | text
|
View definition:SELECT acc_trans.transdate AS "day", sum(acc_trans.amount) AS sum, 
acc_trans.source  FROM acc_trans WHERE acc_trans.source IS NOT NULL GROUP BY acc_trans.transdate, acc_trans.source;

This works OK by itself.

The third view (which is where tthe problem is) is defined thuswise:      View "reporting.day_source"Column |
Type      | Modifiers
 
--------+------------------+-----------day    | date             |source | text             |amount | double precision
|
View definition:SELECT day_inc_source."day", day_inc_source.source, 
COALESCE(day_source_pre.amount, day_inc_source.sum * -1::double 
precision) AS amount  FROM reporting.day_source_pre  RIGHT JOIN reporting.day_inc_source ON day_source_pre.amount = 
day_inc_source.sum AND day_source_pre."day" = day_inc_source."day" WHERE (day_inc_source.source IN ( SELECT
payment_types.id    FROM payment_types)) ORDER BY day_inc_source."day";
 


The problem seems to be somehow assuming that all amount columns in 
day_source_pre are null.  Is there something wrong in how this view is 
working, or is it (more likely) my SQL syntax?

That I want to do is fill in a value from day_inc_source if and only if 
it is not found in day_source_pre with the same date and amount.

Best Wishes,
Chris Travers
Metatron Technology Consulting