Re: Why select * from function doesn't work when function - Mailing list pgsql-hackers

Nigel J. Andrews wrote:

> On Thu, 24 Jul 2003, Francisco Figueiredo Jr. wrote:
> 
> 
>>Nigel J. Andrews wrote:
>>
>>
>>>On Tue, 22 Jul 2003, Francisco Figueiredo Jr. wrote:
>>>
>>>
>>>
>>>>>How's this for an alternative if you really don't want any rows returned:
>>>>>
>>>>>create function fincF ( )  returns setof integer as '
>>>>>begin
>>>>>  delete from blah;
>>>>>  return;
>>>>>end;
>>>>>' language 'plpgsql';
>>>>>
>>>>>
>>>>
>>>>This works, but what I really want is not to return any rows. I mean, 
>>>>the problem is not return null, but the error I get if I select * from 
>>>>voidfunction.
>>>>
>>>>I just wanted void functions behave like others when called as select * 
>>>
>>>>from voidfunction  So I dont have to do select voidfunction. :)
>>>
>>>
>>>But that last does exactly that. Doesn't even return a null. Give it a quick
>>>go, skip the delete statement obviously, and see. You'll get something like:
>>>
>>>   ?
>>>-------
>>>
>>>(0 rows)
>>>
>>
>>
>>Uhmmm, I think I didn't make myself clear. What I mean by void function 
>>wasn't a function which just doesn't return anything. What I meant is a 
>>function created like this:
>>
>>create function voidfunction returns *void* as [...]
> 
> 
> I knew what you meant but why the insistence on the void return type? All it's
> saying is that there isn't any interpretation that can be applied to anything
> that may (or may not) be returned from it so what are you trying to gain by
> forcing the void type when you're forced into ignoring the result anyway?
> 

Oh, good. I thought I was being a little confused and could be leading 
to some misunderstand. :)

I was faced by this when I received a bug report on Npgsql 
(http://gborg.postgresql.org/project/npgsql/bugs/bugupdate.php?554) 
about functions with void result wasn't being able to execute.

The problem is that internally, to get support of returning resultsets 
from function calls, I was calling all functions with select * from 
function. As I could call it this way regardless the function returned 
just a single value or a resultset. I wasn't aware of the void type and 
as Tom Lane also said now, other pseudotypes. So, I thought it was just 
the void type which had this problem, and I was asking about why it 
would behave differently from other types. I thougth it could be some 
missing type, and would be a easy fix. But now I see it isn't so simple :)



> 
>>The problem to me is the void in the returns ;)
>>
>>If you create a function with the returns void above you'll see that if 
>>you do select * from voidfunction it gives you the error I said. But it 
>>works with select voidfunction.
> 
> 
> Well don't create the function as returning void :)
> 

:)

> 
>>I just wanted it to work with select * from voidfunction too. :)
>>
> 
> 
> I think I did most of mine as returning integer type and the value 1 (just for
> something to return).
> 

Yeah, this also would work.

Thanks Nigel for all your feedback.


-- 
Regards,

Francisco Figueiredo Jr.

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