Column default

Hi All,

I am having difficulty understanding the use of defaults.

I have a table with defaults defined in three columns. When I run a function
that inserts/or updates records the default value is not written into the
record. I thought this was a result of updates occurring and not inserts.
So, I changed the source table to have the same defaults. However when I use
the COPY command to place data in the source table the defaults do not appear
to be applied there either.

When I run a query on the table specifying WHERE ptos_uom_factor ISNULL I get
lots of records back. I though that using a default would prevent this outcome.

When is the default value applied? On INSERT? UPDATE? COPY? None of the above?

TIA

Column | Type | Modifiers

----------------------+------------------------+--------------------------------
-
id | character varying(20) | not null
description | character varying(30) | not null
item_class | smallint | not null
inactive | boolean | not null
sales_description | character varying(160) |
purchase_description | character varying(160) |
last_unit_cost | real | not null
costing_method | smallint | not null
sales_gl_account | character varying(15) |
inventory_gl_account | character varying(15) |
cogs_gl_account | character varying(15) |
item_type | character varying(8) |
unit_of_measure | character varying(6) | default 'ea'::character varying
weight | real |
reorder_point | real |
reorder_quantity | real |
purchase_uom | character varying(6) | default 'ea'::character varying
ptos_uom_factor | real | default 1

Kind Regards,
Keith