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From Juergen Saar <juer...@jsaar.org>
Subject Re: Order By Expression
Date Wed, 17 Mar 2010 06:10:02 GMT
Don't know what you expect, but the statement is really strange ...

I Know:
SELECT * FROM artist where artist_name = 'Tom';

Or
SELECT * FROM artist ORDER BY artist_name DESC;

or did you mean:
SELECT * FROM artist where artist_name like 'Tom%' ORDER BY artist_name
DESC;

I think you should know a little about SQL before starting with cayenne ...


The third statement would look like:

SelectQuery query = new SelectQuery(Artist.class);
query.addExpression(ExpressionFactory.likeExp("artistName","Tom");
query.addOrdering("artistName", SortOrder.DESCENDING);
context.performQuery(query);

For the Attribute-Names you should use the static Strings in the
Artist-Class


2010/3/16 Dave Dombrosky <dombrd@gmail.com>

> Yes I'm using Cayenne 3.  I'm not sure if I stated the problem in
> enough detail, because it seems like you guys are confused.  Or maybe
> I just don't understand how to use what you are telling me about.
>
> Maybe it would be better if I was helped with a full example.  Using
> the Artist class from Cayenne's test schema, how would I go about
> creating a SelectQuery to order all artists with the name "Tom" first?
>  Basically to generate a query similar to this:
>
> SELECT * FROM artist ORDER BY artist_name = 'Tom' DESC;
>
> Would it be like this?
>
> SelectQuery query = new SelectQuery(Artist.class);
> query.addOrdering("artistName = 'Tom'", SortOrder.DESCENDING);
> context.performQuery(query);
>
> Because that still gets the error Unsupported ordering expression:
> artistName = 'Tom'.
>
> Am I doing something wrong, or is this impossible with a SelectQuery?
> I'd rather not use SQLTemplate if I can avoid it.
>
> -Dave
>
> On Tue, Mar 16, 2010 at 8:39 AM, Michael Gentry <mgentry@masslight.net>
> wrote:
> > Hi Dave,
> >
> > Since you are seeing deprecation warnings I'm assuming you are using
> > Cayenne 3?  If so, you should use:
> >
> > addOrdering(Ordering ordering) or
> > addOrdering(String sortPathSpec, SortOrder order)
> >
> > These are defined for your SelectQuery object.  Of course, if you are
> > using the first of those methods, you'll have to create your own
> > Ordering object first.  The second creates one for you behind the
> > scenes.
> >
> > Let me know if you need additional pointers!
> >
> > mrg
> >
> >
> > On Tue, Mar 16, 2010 at 1:11 AM, Dave Dombrosky <dombrd@gmail.com>
> wrote:
> >> Is there any way to use sort expressions in a query?  Something like
> >> "ORDER BY column = id"?  I get the error "Unsupported ordering
> >> expression" when trying to execute a query with this in it.
> >>
> >> Also, it looks like I might be able to do this using in-memory
> >> sorting, but the Ordering(Expression sortExpression, ...) methods are
> >> deprecated.  So what's the preferred way to sort on expressions in
> >> Cayenne?
> >>
> >> -Dave
> >>
> >
>

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