Re: Kind of error-handler in a pgsql function - Mailing list pgsql-sql

From DI Hasenöhrl
Subject Re: Kind of error-handler in a pgsql function
Date
Msg-id 002801c10528$cfe35f20$01011eac@irina
Whole thread Raw
In response to Re: Kind of error-handler in a pgsql function  (Alex Pilosov <alex@pilosoft.com>)
Responses Re: Kind of error-handler in a pgsql function
List pgsql-sql
Thank you for your example.
I understand, in order to avoid inserting *duplicate keys*, first I try to update, when it fails make an insert. But other errors may occur, is there a possibility to distinguish between errors by an error-number.
Please can you tell me, where I can find system functions, variables like *diagnostics, row_count, found, and so on.....*
 
Many thanks in advance
Irina
 
You must do it the other way around:

First, try update, then see how many records were updated, if there were 0
records updated, then do the insert.

Currently, plpgsql lacks decent exception handling.

Sample code:

create function ...
...
declare rec_affected int;
begin
  update ...
  get diagnostics rec_affected = ROW_COUNT;
  if rec_affected = 0 then 
    insert ...
  end if;
end;

On Wed, 4 Jul 2001, [iso-8859-1] DI Hasenöhrl wrote:

> Hi,
>
> When I write in psql:
> testdb=# update table1 set tableattribute='any' where table_nr=1;
>     if a tuple exists, I get this message
> testdb=# update 1
>     if no tuple with table_nr=1 exists, I get this message
> testdb=# update 0
>    
>
> Is there a possibility to make a difference in a pgsql function like this:
> create function updTable(text,integer) returns int AS
> 'DECLARE
>    msg ALIAS FOR $1;
>    nr    ALIAS FOR $2;
>  BEGIN
>      update table1 set tableattribute=msg where table_nr=nr;
>      --pseudocode
>        if update = 0 then
>          return 0;
>        else
>          return 1;
>        end if;
>    END;
> 'language 'plpgsql';
>
> or for a function, which inserts data:
> create function insTable(text,integer) returns int AS
> 'DECLARE
>    msg ALIAS FOR $1;
>    nr    ALIAS FOR $2;
>  BEGIN
>      insert into table1 values (nr,msg);
>      --pseudocode
>        if error= cannot insert duplicate key.....then
>          return 0;
>        else
>          return 1;
>        end if;
>    END;
> 'language 'plpgsql';
>
> I want to know the result of an insert or update, because I call these functions from an Access form and the next steps of the program depend on these results.
>
> I hope, someone can help me, because I didn't find anything in the docu or mailing list.
> Thanks in advance
> Irina
>
> E-Mail: i.hasenoehrl@aon.at
>


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