Maybe the reason is that you defined the function to return bool, but are
attempting to return text?
You need conditional logic, which suggests pl/pgsql is the way to go.
Something simple should do it, like:
create function check_loan (text,int,int)
returns bool
as '
begin
select * from loans where typetable=$1 and code_user=$2 and code_loan=$3;
if found then return true;
else return false;
end if;
return true;
end;
' language 'plpgsql';
Since this is your project, I will take the luxury of not testing that code
:-)
----- Original Message -----
From: "Miguel González" <iafmgc@unileon.es>
To: "Haller Christoph" <ch@rodos.fzk.de>
Cc: "PostgreSQL SQL" <pgsql-sql@postgresql.org>
Sent: Wednesday, September 19, 2001 1:55 PM
Subject: Creating a boolean function
> by the way you know how to create the following sql function?
>
> I need to return a boolean saying if an object is onloan.
>
> the loan table is as follows:
>
> loans
> -----
> code_loan
> code_user
> typetable
>
>
> i want to check these three fields, the first two fields (the code ones)
are
> integer and the last a string.
>
> I tried
>
> create function check_loan (text,int,int)
> returns bool
> as
> 'select CAST(typetable AS text) from loans where typetable=$1 and
> code_user=$2 and code_loan=$3;'
> language 'sql';
>
>
> But I got that the parser cannot identify the =$ operator and requires me
to
> do the proper casting.
>
> How can I do it? Sorry for the questions, but I am new at creating
functions
> and I have to hand in this project tomorrow.
>
> Many thanks
>
> Miguel
>
>
>
>
>
>
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