Re: Column default

--- Keith Worthington <keithw(at)narrowpathinc(dot)com>
wrote:

> 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?

A default will be applied on INSERT, if you do not
supply a value for that column. My understanding (I
haven't tested this lately) is that COPY will cause
the default to be applied, if you supply a column list
to the COPY command, not including the column with the
default value.

The most powerful and flexible way to limit or test
the values that are entered into a column is with a
trigger.

>
> 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
>
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