Thread: DROP TYPE without error?

DROP TYPE without error?

From
"Philippe Lang"
Date:
Hi,

Since it is not possible to use CREATE OR REPLACE TYPE, is there a way
of using DROP TYPE on a non-existing type, without causing the entire
script to abort? It may sound crazy to ask for this, but it could be
really useful in my case, where Pl/Pgsql and Pl/Perl code is being
generated automatically, based on data found in a database.

Thanks

-----------------
Philippe Lang



Re: DROP TYPE without error?

From
Mischa
Date:
Quoting Philippe Lang <philippe.lang@attiksystem.ch>:

> Since it is not possible to use CREATE OR REPLACE TYPE, is there a way
> of using DROP TYPE on a non-existing type, without causing the entire
> script to abort? It may sound crazy to ask for this, but it could be
> really useful in my case, where Pl/Pgsql and Pl/Perl code is being
> generated automatically, based on data found in a database.

I've got a similar request for other objects that do/do not exist.
Maybe it's just that I got lazy using MSSQL, but it sure was convenient
to have:
  IF object_id('WorkTable') IS NULL      CREATE TABLE WorkTable(...
etc.

Given that you cannot just execute an anonymous block of PL/PGSQL code,
where you could do the test AND the create ...

-- 
"Dreams come true, not free."



Re: DROP TYPE without error?

From
Harald Fuchs
Date:
In article <1112817807.4254408fecadc@webmail.telus.net>,
Mischa <mischa.Sandberg@telus.net> writes:

> I've got a similar request for other objects that do/do not exist.
> Maybe it's just that I got lazy using MSSQL, but it sure was convenient
> to have:

>    IF object_id('WorkTable') IS NULL
>        CREATE TABLE WorkTable(...
> etc.

I got lazy using MySQL, where it was convenient to have CREATE TABLE IF NOT EXISTS tbl (...)
and DROP TABLE IF EXISTS tbl

This is the only feature of MySQL I really miss.



Re: DROP TYPE without error?

From
Jeff Boes
Date:
Philippe Lang wrote:
> Hi,
> 
> Since it is not possible to use CREATE OR REPLACE TYPE, is there a way
> of using DROP TYPE on a non-existing type, without causing the entire
> script to abort? It may sound crazy to ask for this, but it could be
> really useful in my case, where Pl/Pgsql and Pl/Perl code is being
> generated automatically, based on data found in a database.
> 

If I understand you correctly, then this might be useful:

begin;
select now();

\o tmp.tmp
\qecho 'drop type \"foofookitty\";'
\o
\! psql -f tmp.tmp

select now();
commit;



-- 
Jeff Boes                                         Vox 269-226-9550 x24
Director of Software Development                  Fax 269-349-9076

Exfacto!         Exceptional Online Content     http://www.exfacto.com
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Re: DROP TYPE without error?

From
Craig Addleman
Date:
I was confronted with a similar problem. I have several scripts which create
or modify schemas, and each run in a single transaction. So, dropping a 
non-existent TYPE will produce a show-stopping error. I wrote this function,
and others for various database objects:

CREATE OR REPLACE FUNCTION dba_droptype(varchar) RETURNS boolean AS '
DECLARE  p_type ALIAS FOR $1;  v_exists boolean;
BEGIN  SELECT INTO v_exists TRUE WHERE EXISTS(     SELECT 1 FROM pg_type     WHERE typname = p_type::name);  IF
v_existsTHEN     RAISE NOTICE ''Dropping TYPE %'', p_type;     EXECUTE ''DROP TYPE '' || p_type || '' CASCADE'';  END
IF; RETURN FOUND;
 
END;
' LANGUAGE 'plpgsql';

COMMENT ON FUNCTION dba_droptype(varchar) IS '
Usage: SELECT dba_drop_type(type_name)
Checks for existence of a type and drops it if found.
Implements DROP TYPE CASCADE; if a function or other object
depends on the type, that object will also be dropped. 
Returns TRUE if successful, returns FALSE if type is
not found.';

-- 
Craig Addleman
DBA
ShareChive LLC

* Philippe Lang <philippe.lang@attiksystem.ch> [2005-04-06 05:59]:
> Hi,
> 
> Since it is not possible to use CREATE OR REPLACE TYPE, is there a way
> of using DROP TYPE on a non-existing type, without causing the entire
> script to abort? It may sound crazy to ask for this, but it could be
> really useful in my case, where Pl/Pgsql and Pl/Perl code is being
> generated automatically, based on data found in a database.
> 
> Thanks
> 
> -----------------
> Philippe Lang
> 
> 
> ---------------------------(end of broadcast)---------------------------
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