Re: [JDBC] Selecting Varchar range (through JDBC).

Hi Daryl,

Don't ya just love playing with regex :)

If you think the query is corrupt, try turning on print_query in the
postgresql logs and you can see what the query that the backend is
receiving is there. Chances are that the driver is working.

If you think your regex is wrong just test it with psql. ie, just try
the following...
select 'Art' ~* '^[a-c]';

Regarding your regex, if you want artist names between A and C, the
regex would be: sortName ~* '^[a-c]'

The ~* bit is a case insensitive match.

Hope that helps a little,

Tom.

On Fri, 2002-08-30 at 22:17, Daryl Beattie wrote:
> Dear PostgreSQL people,
>
> Thanks for your help from before, Vince. I didn't get around to
> attempting to implement that varchar range function until last night, and
> when I did I ran into some problems. Whenever I tried to execute the
> statement:
>
> SELECT ArtistId FROM Artist WHERE SortName ~*
> '[[.testArtist1.]-[.testArtist2.]].*'
>
> I get the following JDBC error:
>
> javax.ejb.FinderException: SQLException while finding Artists:
> java.sql.SQLException: ERROR: Invalid regular expression: invalid collating
> element
>
> The SQLException is coming from the database, however, it MAY be a
> JDBC driver issue with it not escaping the statement properly.
> My suspicion, however, is that I'm simply not using the regular
> expressions correctly. Can anybody kindly explain to me how to do this
> correctly? (I am trying to search a varchar range, for example, any Artists
> whose names start with the letters A to C.)
> I have attached my Java code to the bottom of this e-mail for
> reference.
> For your convenience, here's the link to the idocs that describes
> regex functionality in PostgreSQL:
> http://www.postgresql.org/idocs/index.php?functions-matching.html#FUNCTIONS-
> REGEXP
>
> Sincerely,
>
> Daryl.
>
> P.S. Some notes:
> - I'm using PostgreSQL 7.2.1 on RH Linux 7.2, and the latest binary
> PostgreSQL JDBC driver.
> - It doesn't matter what I put in the [. .], it never seems to work
> any better. For example, a good test would be WHERE SortName ~*
> '[[.A.]-[.C.]].*'
> - I tried using a straight Statement-from-a-query-string that I
> constructed instead of a PreparedStatement (to bypass any automatic escaping
> done by the PreparedStatement), and got the same results.
>
>
> > -----Original Message-----
> > From: Vince Vielhaber [mailto:vev(at)michvhf(dot)com]
> > Sent: Monday, August 12, 2002 8:49 AM
> > To: Daryl Beattie
> > Cc: pgsql-general(at)postgresql(dot)org
> > Subject: Re: [GENERAL] Selecting Varchar range.
> >
> >
> > On Mon, 12 Aug 2002, Daryl Beattie wrote:
> >
> > > Dear PostgreSQL people,
> > >
> > > I didn't find this in the archives or the idocs, so...
> > >
> > > How does one select a varchar range? The meaning of my
> > question is
> > > best illustrated by the following completely hypothetical
> > and totally
> > > imaginary situation:
> > > Let's say I have a table of musical artists:
> > >
> > > CREATE TABLE Artists (
> > > Id SERIAL PRIMARY KEY,
> > > Name VARCHAR(100)
> > > );
> > >
> > > And I want to eventually display only the artists from
> > 'Aa' to 'Am'.
> > > Naturally doing a select where Name like 'A%' will not
> > return me what I
> > > want.
> > > Any ides on how to do this? [Will "SELECT Name FROM
> > Artists WHERE
> > > Name > 'Aa%' AND Name < 'Am%';" work?]
> > >
> > > Bonus question: How do I select artists whose names start with a
> > > number?
> >
> > Think REGEX. A[a-m]% [0-9]%
> >
> > If any of your artists are indies, send them to www.unknown-artists.com
> >
> > Vince.
>
>
>
>
>
> /**
> * Finds all of the Artists whose sort-names fall within a particular range,
> * and returns them in a Collection. An example of this would be to ask for
> * all of the artists that are within "Aa" and "Cz", and it would return all
> * the Artists that start with A, B, and C. Case is ignored for the search,
> * but <i>be careful</i> because some bands could start with numbers!
> *
> * @param start The start String of the Artists we want to find.
> * @param end The end String of the Artists we want to find.
> * @return A Collection containing all the Artists whose sort-names fall
> * within a particular range.
> * @throws FinderException If there was a problem finding such Artists.
> */
> public Collection ejbFindArtistsWhoseSortNamesAreWithin(String start, String
> end) throws FinderException {
> ArrayList artists = new ArrayList(); // All of the Artists.
> Connection dbConnection = null; // The database connection.
> PreparedStatement ps = null; // The statement(s) to execute.
> ResultSet resultSet = null; // The results of the query.
>
> if ((start.indexOf("-") > 0) || (start.indexOf("[") > 0) ||
> (start.indexOf("]") > 0) || (end.indexOf("-") > 0) || (end.indexOf("[") > 0)
> || (end.indexOf("]") > 0)) throw new FinderException("The start and end
> strings for findArtistsWhoseSortNamesAreWithin() cannot have '-', '[' or ']'
> in them.");
> if ((start == null) || ("".equals(start)) || (end == null) ||
> ("".equals(end))) return artists;
>
> // STEP 1: Get the database connection.
> try { dbConnection = getConnection(); } catch (Exception e) { throw
> new EJBException(e.getMessage()); }
>
> // STEP 2: Find the Artists.
> try {
> String queryStr = "SELECT " + DatabaseNames.ARTIST_ID + "
> FROM " +
> DatabaseNames.ARTIST_TABLE + " WHERE " +
> DatabaseNames.ARTIST_SORTNAME + " ~* ?";
> ps = dbConnection.prepareStatement(queryStr);
> ps.setString(1, "[[." + start + ".]-[." + end + ".]].*");
> resultSet = ps.executeQuery();
> ArtistPK artistPK = null;
> while (resultSet.next()) {
> artistPK = new ArtistPK();
>
> artistPK.setId(resultSet.getInt(DatabaseNames.ARTIST_ID));
> artists.add(artistPK);
> }
> }
> catch(SQLException e) {
> context.setRollbackOnly();
> throw new FinderException("SQLException while finding
> Artists:\n" + e);
> }
> finally {
> try { closeResultSet(resultSet); } catch (Exception e) {
> log.warning("Failed to close ResultSet: " + e.getMessage()); }
> try { closeStatement(ps); } catch (Exception e) {
> log.warning("Failed to close Statement: " + e.getMessage()); }
> try { closeConnection(dbConnection); } catch (Exception e) {
> log.warning("Failed to close Connection: " + e.getMessage()); }
> }
>
> // STEP 3: Return that Collection of ArtistPKs.
> return artists;
> }
>
> ---------------------------(end of broadcast)---------------------------
> TIP 3: if posting/reading through Usenet, please send an appropriate
> subscribe-nomail command to majordomo(at)postgresql(dot)org so that your
> message can get through to the mailing list cleanly
--
Thomas O'Dowd. - Nooping - http://nooper.com
tom(at)nooper(dot)com - Testing - http://nooper.co.jp/labs