[PyGreSQL] How to insert a record if it doesn't exist else update it ?

[D'Arcy J.M. Cain]

On Wed, 19 Dec 2007 23:39:34 +0800
"fdu.xiaojf at gmail.com" <fdu.xiaojf at gmail.com> wrote:
> Hi all,
> 
> What I want to do is:
>      if a record already exists in the table, update it
>      if a record doesn't exist, insert it into the table

First of all, this is a PostgreSQL question, not a PyGreSQL one.  In
general you will get much better responses if you use the correct
mailing list.  Check out http://www.PostgreSQL.org/ for their mailing
lists.  You probably want the SQL or help list.

> I know that there is a ON DUPLICATE clause with MySQL, so I'm wondering is 
> there a corresponding way to do this in PostgreSQL ?

I don't think so but you can probably do something with rules.  Check
out the PostgreSQL docs.

> Currently the only way I can find is do query first and then update or insert.

I think that you will find this the safest way.  If you know that you
aren't in the middle of a transaction you could use a try/except
statement but this will break your transaction if you are in one.

-- 
D'Arcy J.M. Cain
PyGreSQL Development Group
http://www.PyGreSQL.org