if exists ...

Started by Andreas Schlegelover 23 years ago2 messagesgeneral
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#1Andreas Schlegel
schlegelaw@gmx.de

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

#2Darko Prenosil
darko.prenosil@finteh.hr
In reply to: Andreas Schlegel (#1)
Re: if exists ...

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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