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Re: Null function parameters

From: tolik(at)aaanet(dot)ru (Anatoly K(dot) Lasareff)
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: "Graham Vickrage" <graham(at)digitalplanit(dot)com>, "postgresql" <pgsql-sql(at)postgresql(dot)org>
Subject: Re: Null function parameters
Date: 2000-08-23 11:46:14
Message-ID: 86ya1o8ak9.fsf@tolikus.hq.aaanet.ru (view raw or flat)
Thread:
Lists: pgsql-sql
>>>>> "TL" == Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:

 TL> "Graham Vickrage" <graham(at)digitalplanit(dot)com> writes:
 >> However my understanding was that if the default value is SQL NULL then any
 >> values passed into the function that are null would be treated as 'NULL'.

 TL> Not sure what you think you meant by that, but a null is a null.  If you
 TL> declared the table column as NOT NULL then Postgres is doing exactly
 TL> what it should.  You may wish to code the insert along the lines of

 TL> INSERT INTO table VALUES (..., COALESCE($1, suitable-default), ...)

 TL> COALESCE is a handy notation for "value1 unless it's NULL, in which case
 TL> value2".

 TL> regards, tom lane

But unfortunately we have no answer for primary question:

| Why if we pass to function ONLY ONE null agument all the oters    |
| argumenta in function's boby are null too?                        |
| Or: is it possible to pass null arguments into plpgsql functions? |

Example.

create function a(int, int) returns int as '
begin
  raise notice ''1: % 2: %'', $1, $2;

  if $1 is null then
    return $2;
  end if;

  return $1;
end;
' language 'plpgsql';

tolik=# select a(1,2);
NOTICE:  1: 1 2: 2
 a 
---
 1
(1 row)

tolik=# select a(null,2);
NOTICE:  1: <NULL> 2: <NULL>
 a 
---
  
(1 row)


-- 
Anatoly K. Lasareff              Email:       tolik(at)aaanet(dot)ru 

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Subject: RE: Null function parameters
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