Обсуждение: if exists ...

Hi,

writing Postgres SQL scripts I have the problem: how do I check if a
database object already exists?

Having a list of create table, create trigger, create view ...
statements I have to decide if the script first drops the existing old
object or if it doesn't already exist to create it without dropping.

Transact-Sql allows the following construct:
if exists (select * from sysobjects where id = object_id(...) = 1)
drop trigger tCompUTrig
GO

I know that postgres has the "table_exists" function. But I don't know
the syntax to integrate it in a script with create and drop statements.

Any ideas?

Greetings,
Andreas

On Friday 10 January 2003 14:02, Andreas Schlegel wrote:
> Hi,
>
> writing Postgres SQL scripts I have the problem: how do I check if a
> database object already exists?
>
> Having a list of create table, create trigger, create view ...
> statements I have to decide if the script first drops the existing old
> object or if it doesn't already exist to create it without dropping.
>
> Transact-Sql allows the following construct:
> if exists (select * from sysobjects where id = object_id(...) = 1)
> drop trigger tCompUTrig
> GO
>
> I know that postgres has the "table_exists" function. But I don't know
> the syntax to integrate it in a script with create and drop statements.
>
> Any ideas?
>
> Greetings,
> Andreas
>
>

Maybe functions I wrote can help. You can find it at:
http://www.brasileiro.net:8080/postgres/cookbook/view-one-recipe.adp?recipe_id=4448
Regards.

>
>
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