pgplsql - Oracle nvl

You don't need to build any function for this, you have them ready:
http://www.postgresql.org/docs/view.php?version=7.3&idoc=0&file=functions-conditional.html#AEN9753
http://www.postgresql.org/docs/view.php?version=7.3&idoc=0&file=functions-conditional.html#AEN9698

Cheers,
Csaba.

I know this functions, but I do not want to change the statements in my
old application.
So I want to make the functions with the Oracle names for compatibility.

Best regards,
Christian

Csaba Nagy wrote:

OK, clear.
But if you have access to your application code, it's maybe better to
create an abstraction layer in front of the DB specific SQLs, and
implement for each DB differently (this is how we do it).
The "nvl" and "decode" statements are Oracle specific, so I can't see
why not use the Postgres specific syntax for Postgres. A lot of Oracle
queries will work a lot better on postgres if rewritten differently, and
some of them can be even expressed more elegantly in Postgres. AFAIKT,
designing your application so it can use a DB abstraction layer will
give you far less trouble in the long run than trying to make the Oracle
queries work unchanged on Postgres...

Cheers,
Csaba.

On Wed, Aug 27, 2003 at 09:58:00 +0200,
Christian Traber <christian@traber-net.de> wrote:

Hi,

I'll try to switch from Oracle to postgres for some small applications.
Is it possible to build functions like Oracle's nvl or decode with pgplsql?
How can I make a function like nvl that works for every datatype?

You can use coalesce to do what nvl does.

On Wednesday 27 August 2003 09:58, Christian Traber wrote:

Hi,

I'll try to switch from Oracle to postgres for some small applications.
Is it possible to build functions like Oracle's nvl or decode with pgplsql?
How can I make a function like nvl that works for every datatype?

Write as many "nvl" functions as you have different types of params.
Overloading works just fine in postgres. (I do not know what function "nvl"
actually does, so maybe You can explain it.)

for example :

CREATE OR REPLACE FUNCTION nvl( INTEGER ) AS ...
CREATE OR REPLACE FUNCTION nvl( TEXT ) AS ...

Regards !

Write as many "nvl" functions as you have different types of params.
Overloading works just fine in postgres. (I do not know what function "nvl"
actually does, so maybe You can explain it.)

It's the same as coalesce in postgres.
If overloading works, my problem is solved:-)

Thanks,
Christian

Hi,

I'll try to switch from Oracle to postgres for some small applications.
Is it possible to build functions like Oracle's nvl or decode with
pgplsql?
How can I make a function like nvl that works for every datatype?

Best regards,
Christian

Try coalesce. The syntax is the same as nvl.

Jeff

If you want to keep the same functions just do as follows

CREATE OR REPLACE FUNCTION nvl(TEXT,TEXT) RETURNS TEXT AS '
BEGIN
RETURN COALESCE($1,$2);
END;' LANGUAGE 'plpgsql';

You will have to do this for all supported data types unless you want to
put in a third parameter that would be the cast type

HTH

Darren

On Wed, 27 Aug 2003, Christian Traber wrote:

I know this functions, but I do not want to change the statements in my
old application.
So I want to make the functions with the Oracle names for compatibility.

Best regards,
Christian

Csaba Nagy wrote:

You don't need to build any function for this, you have them ready:
http://www.postgresql.org/docs/view.php?version=7.3&amp;idoc=0&amp;file=functions-conditional.html#AEN9753
http://www.postgresql.org/docs/view.php?version=7.3&amp;idoc=0&amp;file=functions-conditional.html#AEN9698

Cheers,
Csaba.

On Wed, 2003-08-27 at 09:58, Christian Traber wrote:

Hi,

I'll try to switch from Oracle to postgres for some small applications.
Is it possible to build functions like Oracle's nvl or decode with pgplsql?
How can I make a function like nvl that works for every datatype?

Best regards,
Christian

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