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Re: InstantDB: ORDER BY CollationKey?


Hi Dick

> 1) In your example, what java methods does the order clause
>   use to compare java.lang.Object's that are returned by the
>   function "lower"?  That is, what methods are used to compare 
>   arbitrary objects that are returned by the evaluate method of 
>   the sqlFunction interface?

It knows they're strings that get returned from the lower function, so 
it'll do java.lang.String.equals or compareTo on them.

> 2) I suppose that my orginal question boils down to: can
>   order clauses be used on BINARY columns?

Not really. I think it'll accept ORDER BY on binaries, but the default 
collation sequence is just to just compare their lengths - not very 
useful. You really would need to write a function to do something 
sensible with these.

> Although the idea of writing my own sql function is attractive,
> I may shy away from it because I assume that it will reduce the
> degree to which my application is portable.  (I have no idea
> how general the notion of user-defined sql functions really is.)

IDB's way of doing this is totally non-portable. I guess you would 
write a callable SQL function in PL/SQL for something like Oracle. I 
think it'd be pretty different whatever database you migrated to.

FWIW, the little bit of SQL I sent in my earlier mail should be pretty 
portable though.

Pete
----- Original Message -----
From: Dick Repasky <drepasky@bio.indiana.edu>
Date: Sunday, December 10, 2000 5:36 pm
Subject: Re: InstantDB: ORDER BY CollationKey?

> Pete,
> 
> Thanks for the reply, and on Sunday, no less!
> 
> Two questions: one about your suggestion and one about my original
> post.
> 
> 
> 2) I suppose that my orginal question boils down to: can
>   order clauses be used on BINARY columns?
>   
> Although the idea of writing my own sql function is attractive,
> I may shy away from it because I assume that it will reduce the
> degree to which my application is portable.  (I have no idea
> how general the notion of user-defined sql functions really is.)
> 
> Thanks,
> 
> Dick
> 
> Most recent message:
> > From: Peter Hearty <peter.hearty@lutris.com>
> > To: instantDB@enhydra.org
> > Date: Sun, 10 Dec 2000 15:39:07 GMT
> > Subject: Re: InstantDB: ORDER BY CollationKey?
> >
> >Dick
> >
> >Don't know if this is exactly what you asked for, but this 
> extract from 
> >a ScriptTool script illustrates how to alter the collation 
> sequence 
> >using a string function
> >
> >drop table test;
> >create table test (id int, name char(40) );
> >insert into test values (1, "Zog");
> >insert into test values (2, "alan");
> >q select * from test order by name;
> >q select lower(name),test.* from test order by 1;
> >
> >As you can write your own functions, you can effectively have any 
> >collation sequence that you like.
> >
> >Regards
> >
> >Pete
> >
> >----- Original Message -----
> >From: Dick Repasky <drepasky@bio.indiana.edu>
> >Date: Sunday, December 10, 2000 2:13 am
> >Subject: InstantDB: ORDER BY CollationKey?
> >
> >> 
> >> Hello, all,
> >> 
> >> This is my first post.
> >> 
> >> I'd like to use the ORDER clause on strings and have them be 
> ordered>> as they would be by a java Collator.  (What counts is 
> that lower and
> >> upper cases be honored but grouped together by first letter 
> rather 
> >> thanappearing as all upper case instances of all letters 
> followed 
> >> by all
> >> lower case instances of all letters.  I'm also interested in 
> >> supportingmultiple languages.)  I understand that this is not 
> >> possible in instantdb
> >> by default.
> >> 
> >> The question is: can I obtain the desired effect by using a 
> table 
> >> columnthat contains CollationKeys and use the ORDER clause on 
> the 
> >> key column?
> >> The idea is to use the toByteArray() method of CollationKey to 
> get a
> >> plain form of the keys and then put the bytes into a column of type
> >> BINARY in the table and use ORDER on that column.  Presto?
> >> 
> >> Thanks,
> >> 
> >> Dick
> >> ----------------------------------------------------------------
> ---
> >> ----------
> >> To unsubscribe from this mailing list, send email to 
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> the 
> >> body of the email.
> >> If you have other questions regarding this mailing list, send 
> >> email to
> >> the list admin at owner-instantdb@enhydra.org.
> >> 
> >
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> >
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