RE: select on multiple tables

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От Dave Cramer
Тема RE: select on multiple tables
Дата
Msg-id 00cf01c129d5$d83bb8d0$c201a8c0@inspiron
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Ответ на Re: select on multiple tables  (Rene Pijlman <rpijlman@wanadoo.nl>)
Ответы RE: select on multiple tables
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Unfortunately id doesn't return A.c and B.c. Try it in psql...

One way to solve this is to fix the backend to return fully qualified
column names.

Dave

-----Original Message-----
From: pgsql-jdbc-owner@postgresql.org
[mailto:pgsql-jdbc-owner@postgresql.org] On Behalf Of Rene Pijlman
Sent: August 20, 2001 3:49 PM
To: Carterette, Ben
Cc: 'pgsql-jdbc@postgresql.org'
Subject: Re: [JDBC] select on multiple tables


On Mon, 20 Aug 2001 12:50:22 -0500, you wrote:
>The SELECT is in a servlet, something like this:
>
>rs = stmt.executeQuery("SELECT * FROM " +
>request.getParameter("table1") + ", " +
>request.getParameter("table2")); session.setAttribute("result", rs);
>request.sendRedirect(request.getParameter("page2"));
>
>that's a simplification of what it does, but it's good enough for
>demonstration I think.
>
>The .jsp file that calls the servlet knows what tables it wants to read

>out of, and the .jsp file that the servlet redirects to knows what
>columns it wants.  The servlet doesn't know anything and hopefully
>shouldn't care.  I wanted to abstract it as much as possible.

How about using ResultSetMetaData.getColumnName() on the ResultSet to
dynamically query the column names? See:
http://java.sun.com/j2se/1.3/docs/api/java/sql/ResultSetMetaData.html

I don't know that this will (and should) return when you do SELECT *
from A, B and there is a column c in both tables. Hopefully it returns
A.c and B.c.

Regards,
René Pijlman

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