Re: Column default
От | Jeff Eckermann |
---|---|
Тема | Re: Column default |
Дата | |
Msg-id | 20050214200420.40185.qmail@web20828.mail.yahoo.com обсуждение исходный текст |
Ответ на | Column default ("Keith Worthington" <keithw@narrowpathinc.com>) |
Список | pgsql-novice |
--- Keith Worthington <keithw@narrowpathinc.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 > > ---------------------------(end of > broadcast)--------------------------- > TIP 3: if posting/reading through Usenet, please > send an appropriate > subscribe-nomail command to > majordomo@postgresql.org so that your > message can get through to the mailing list > cleanly > __________________________________ Do you Yahoo!? Yahoo! Mail - Find what you need with new enhanced search. http://info.mail.yahoo.com/mail_250
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