Re: How to avoid nulls while writing string for dynamic query

Thanks Tomasz Myrta. It is wonderful. I am still amazed from where you guys
knowing the options like quote_literal, etc.

Kumar

----- Original Message -----
From: "Tomasz Myrta" <jasiek(at)klaster(dot)net>
To: "Kumar" <sgnerd(at)yahoo(dot)com(dot)sg>
Cc: "psql" <pgsql-sql(at)postgresql(dot)org>
Sent: Friday, February 13, 2004 1:37 PM
Subject: Re: [SQL] How to avoid nulls while writing string for dynamic query

> Dnia 2004-02-13 08:13, Użytkownik Kumar napisał:
> > oh, ok understood.
> > What will happen for a timestamp field. Let us say c1 is a timestamp
column.
> >
> > sqlstr := 'insert into test(c1, c2) values
> > ('||'\''||COALESCE(rec.c1,'NULL')||'\','
> >
> >>> ||'\''||rec.c2||'\')';
> >
> >
> > If this case the query will be
> > insert into test(c1,c2) values ('2004-02-13', 'Hai')
> >
> > If there is a null value encountered i will return an error for the
> > following query
> > insert into test(c1,c2) values ('NULL', 'Hai')
> > ERROR: Bad timestamp external representation 'NULL'
> It's because you can't use quotes with null. Valid query is:
> insert into test(c1,c2) values (NULL, 'Hai');
>
> Your dynamic query will then look like:
>
> sqlstr := 'insert into test(c1, c2) values (' ||COALESCE('\'' || rec.c1
> || '\'','NULL') ...
>
> or more elegant:
>
> sqlstr := 'insert into test(c1, c2) values ('
> ||COALESCE(quote_literal(rec.c1),'NULL') ...
>
> Regards,
> Tomasz Myrta