Re: Moving from Sybase to Postgres - Stored Procedures

Andre Schnoor wrote:
> "Joshua D. Drake" wrote:
>
>>Andre Schnoor wrote:
>>
>>>Hi,
>>>
>>>I am moving from Sybase to pgsql but have problems with stored procedures.
>>>The typical procedure uses
>>>
>>>a) named parameters,
>>>b) local variable declarations and assignments
>>>c) transactions
>>>d) cursors, views, etc.
>>>
>>>I can't seem to find these things in the Postgres function syntax.
>
>
> [...]
>
>
>>Perhaps if you provided the actual problem? Is there a specific
>>procedure that you are trying to port that you do not understand in the
>>PgSQL sense?
>
>
> Thank you for asking, Joshua. I've put an example procedure skeleton here:
>
> CREATE PROCEDURE do_something
> @song_id int,
> @user_id int,
> @method int,
> @length int = 0,
> @date_exact datetime,
> @default_country int = null
> AS
> -- temporary variables
> DECLARE
> @artist int,
> @sample int,
> @date varchar(32),
> @country int
> BEGIN
> -- assign temporary variables
> select @date = convert(varchar(32),@date_exact,101)
> select @artist = user_id, @sample = is_sample from sto_song where song_id = @song_id
> -- perform conditional code
> if (@sample = 1) begin
> begin transaction
> ... do something ...
> commit transaction
> end else begin
> ... do something else ...
> end
> -- return results
> select
> result1 = ... some expression ...,
> result2 = ... another expression ...
> END
>
> I could not yet translate this to PgSQL, as I can't find any control structures, variable declaractions, etc.
>
I think what you want is plpgsql (which needs to instantiated on the
database in question)
createlang -U postgres plgsql dbname (for example)

The documentation is pretty decent on the language itself: for example:

CREATE FUNCTION somefunction (integer, integer, timestamp) RETURNS
[setof] datatype AS $$
DECLARE
-- alias the passed arguments
thesong_id ALIAS FOR $1;
theuser_id ALIAS FOR $2;
datetime ALIAS FOR $3;
-- temporary variables
artist int;
sample int;
thedate date;
BEGIN
thedate := datetime::date;
SELECT INTO artist user_id from sto_song where song_id = thesong_id;
SELECT INTO sample is_sample from sto_song where song_id = thesong_id;
IF sample = 1 THEN
-- do stuff
ELSE
-- do other stuff
END IF;
RETURN something;
END;
$$ LANGUAGE plpgsql;

See if that helps you ... it really looks as though the languages are
similar enough that moving the stored procedures should a fairly decent
proposition.

Sven