Res: SELECT with WHERE clause by column number

All my columns have the same data type: text.
So it's much easier.

Carlos Henrique Iazzetti Santos
Compels Informática
Santa Rita do Sapucaí - MG
www.compels.net

----- Mensagem original ----
De: Richard Huxton <dev(at)archonet(dot)com>
Para: Carlos Santos <carlos(at)compels(dot)net>
Cc: Lista PostgreSQL SQL <pgsql-sql(at)postgresql(dot)org>
Enviadas: Segunda-feira, 18 de Dezembro de 2006 15:25:27
Assunto: Re: [SQL] SELECT with WHERE clause by column number

Carlos Santos wrote:
> SELECT id FROM myTable WHERE column-number = 'value';
> (PS: The id column is the primary key of myTable).
>
> That is a select using column number in the WHERE clause what don't exists in SQL.
>
> I need this because there's a situation in my program where I don't have the column name.
> I've solved that querying Postgresql the name of the column with that number, and then creating the SELECT query.
> But this solution is slow... two database calls...

If you don't know what the column is, how do you know what you are
testing against? Or what type it is, for that matter?

Anyway, just have build a list of column-name,column-type pairs for
relevant tables at application start-up, or store it in a configuration
file. Unless you're building/changing tables all the time, that should work.

I'm curious as to what type of application can usefuly query a database
without knowing what structure it has.

--
Richard Huxton
Archonet Ltd

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