Обсуждение: PL/SQL trouble

Hi,

I really don't understand following PostgreSQL 7.2.3 behaviour:

$ psql mydb
mydb=> CREATE FUNCTION MONDAY(timestamp) RETURNS DATE AS 'DECLARE  var1 date;BEGIN select into var1
to_date($1::date-(casewhen extract(DOW from
 
timestamp $1) = 0 then 6 else (extract(DOW from timestamp $1)-1) end)); RETURN var1;END'
language 'plpgsql';

CREATE
mydb=> select MONDAY('now'::timestamp);
NOTICE:  Error occurred while executing PL/pgSQL function MONDAY
NOTICE:  line 4 at select into variables
ERROR:  parser: parse error at or near "$2"
mydb=> \q

But I've not inserted any $2 there.
I've rewritten the same function in other ways but I've got the same error.

I thank you in advance for any hints.


Bye,                 \fer

On Tuesday 26 Nov 2002 8:56 am, Ferruccio Zamuner wrote:
> CREATE FUNCTION MONDAY(timestamp) RETURNS DATE AS '
>  DECLARE
>   var1 date;
>  BEGIN
>   select into var1 to_date($1::date-(case when extract(DOW from
> timestamp $1) = 0 then 6 else (extract(DOW from timestamp $1)-1) end));
>   RETURN var1;
>  END'
> language 'plpgsql';

The problem is the to_date(...) - the value is already a date so there isn't a
to_date that takes a date. You can also remove the timestamp casts:

select into var1 ($1::date - (case when extract(DOW from $1) = 0    then 6   else (extract(DOW from $1) - 1 ) end )
);

If you put your function in a text file and create it with psql -f you can
pinpoint errors more easily.

In this case, the $2 was complaining about the second (expected) paramater to
to_date I think.
--  Richard Huxton

> I really don't understand following PostgreSQL 7.2.3 behaviour:
>
> $ psql mydb
> mydb=> CREATE FUNCTION MONDAY(timestamp) RETURNS DATE AS '
>  DECLARE
>   var1 date;
>  BEGIN
>   select into var1 to_date($1::date-(case when extract(DOW from
> timestamp $1) = 0 then 6 else (extract(DOW from timestamp $1)-1)
end));
>   RETURN var1;
>  END'
> language 'plpgsql';
>
> CREATE
> mydb=> select MONDAY('now'::timestamp);
> NOTICE:  Error occurred while executing PL/pgSQL function MONDAY
> NOTICE:  line 4 at select into variables
> ERROR:  parser: parse error at or near "$2"
> mydb=> \q
>
> But I've not inserted any $2 there.
> I've rewritten the same function in other ways but I've got the same
error.
>

Something like the following works (as Richard already pointed out):
CREATE OR REPLACE FUNCTION MONDAY(timestamp) RETURNS DATE AS 'DECLARE ts_param    ALIAS FOR $1; var1 date;BEGIN select
intovar1 to_date(ts_param::date- (case when extract(DOW from ts_param) = 0 then 6 else (extract(DOW from ts_param)-1)
end),''DD'');RETURN var1;END'
 
language 'plpgsql';

Me personally would prefer another approach:
CREATE OR REPLACE FUNCTION MONDAY(timestamp) RETURNS DATE AS 'DECLARE ts_param    ALIAS FOR $1; var1 date; var2 double
precision;BEGINvar2 := extract(DOW from ts_param); IF var2 = 0 THEN  var2 := 6; ELSE  var2 := var2 - 1; END IF; var1 :=
to_date(ts_param::date- var2,''DD'');RETURN var1;END'
 
language 'plpgsql';
because it's easier to read, but that's only a matter of taste I
suppose.

Regards, Christoph