Postgres Pro
Downloads
Home   >   mailing lists

Thread: Dynamic Query problem

Dynamic Query problem

From
"Dinesh Parikh"
Date:
Dear All,
I am new in postgres there for i have some problems. I am executing some type of Business rule in strored procedure using language plpgsql. When I am executing a Dynamic Query then It return an error which is some how unable to understand Please Help me It is urgent . I am attaching my code as well as error which appears to me.
I have noted that if table has same type of column then no error comes .
 
I am using RedHat 7.1 and postgres 7.1.2
Thanks
 
Regards
Dinesh Parikh
NSTL, New Delhi.
 
 
Function Code is described as:
drop function testfunc();
Create function testfunc()
returns int4 as '
Declare
        Query text;
        MyRec   Record;
        DBColName Text;
        DBOut   Text;
        DBCount int4 := 1;
Begin
        DBColName := ''X_1'';
        For i In 1 ..10
        Loop
                If (DBCount =1 ) Then
                        DBColName := ''X_2'';
                        DBCount :=2;
                Else
                        DBColName := ''X_1'';
                        DBCount := 1;
                End If;
                Query := '' Select ''|| DBColName || '' As Field '' || '' From TestTable '';
                For MyRec In Execute Query
                Loop
                    Raise Notice '' MyRec.Field = %'',MyRec.Field;
                    DBOut := MyRec.Field;
                    Raise Notice ''DBOut = %'',DBOut;
                End Loop
        End Loop;
        Return null;
end;
'language 'plpgsql';
 
I have a table TestTable(X_1 int4, X_2 Int8);
 
Error Appeared as:
 
Jurassik=# select testfunc();
NOTICE:  MyRec.Field = 211
NOTICE:  DBOut = 211
NOTICE:  MyRec.Field = 221
NOTICE:  DBOut = 221
NOTICE:  MyRec.Field = 231
NOTICE:  DBOut = 231
NOTICE:  MyRec.Field = 241
NOTICE:  DBOut = 241
NOTICE:  MyRec.Field = 21
ERROR:  type of myrec.field doesn't match that when preparing the plan
 
 

Re: Dynamic Query problem

From
Stephan Szabo
Date:
On Fri, 28 Sep 2001, Dinesh Parikh wrote:

> Dear All,

> I am new in postgres there for i have some problems. I am executing
> some type of Business rule in strored procedure using language
> plpgsql. When I am executing a Dynamic Query then It return an error
> which is some how unable to understand Please Help me It is urgent . I
> am attaching my code as well as error which appears to me.

> I have noted that if table has same type of column then no error comes
> .

My guess would be that the offending line is the DBOut := MyRec.field
since when you go from X_1 to X_2 the right hand side changes type.
It probably planned out how to do the assignment/conversion for the
int4 column and then an int8 is there.

> ERROR:  type of myrec.field doesn't match that when preparing the plan

Re: Dynamic Query problem

From
"Dinesh Parikh"
Date:
Hi,
Actually I think there is some type of caching in record datatype. Is there
any way to find datatype of record's column so that i can explicit cast in
assignment(have u propse alternate of this).

Regards
Dinesh
NSTL, New Delhi

----- Original Message -----
From: "Stephan Szabo" <sszabo@megazone23.bigpanda.com>
To: "Dinesh Parikh" <dineshp@newgen.co.in>
Cc: <pgsql-general@postgresql.org>
Sent: Saturday, September 29, 2001 12:02 PM
Subject: Re: [GENERAL] Dynamic Query problem


>
> On Fri, 28 Sep 2001, Dinesh Parikh wrote:
>
> > Dear All,
>
> > I am new in postgres there for i have some problems. I am executing
> > some type of Business rule in strored procedure using language
> > plpgsql. When I am executing a Dynamic Query then It return an error
> > which is some how unable to understand Please Help me It is urgent . I
> > am attaching my code as well as error which appears to me.
>
> > I have noted that if table has same type of column then no error comes
> > .
>
> My guess would be that the offending line is the DBOut := MyRec.field
> since when you go from X_1 to X_2 the right hand side changes type.
> It probably planned out how to do the assignment/conversion for the
> int4 column and then an int8 is there.
>
> > ERROR:  type of myrec.field doesn't match that when preparing the plan

Re: Dynamic Query problem

From
Stephan Szabo
Date:
On Sat, 29 Sep 2001, Dinesh Parikh wrote:

> Hi,
> Actually I think there is some type of caching in record datatype. Is there
> any way to find datatype of record's column so that i can explicit cast in
> assignment(have u propse alternate of this).

Well, you could explicitly cast in the select query string to the type you
want it to be. Something like:
''Select '' || DBColName || ''::<type> As Field '' || '' From TestTable''
where <type> is the type you want out.