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Posted to user@cayenne.apache.org by Joshua Pyle <jo...@gmail.com> on 2006/05/24 19:59:25 UTC
Re: Query Examples Needed – Expression.fromString() syntax?
I never use fromString any more.
But using the expressionFactory to and and or expressions is very simple...
Expression e = ExpressionFactory.greaterExp("estimatedPrice", new
BigDecimal(100000.0));
e = e.and( ExpressionFactory.lessExp("estimatedPrice", new
BigDecimal(5000.0)) );
--
Joshua T. Pyle
Go has always existed.
On 5/24/06, Eric Lazarus <er...@yahoo.com> wrote:
> Would anyone reply with some nice examples of
> SelectQuery beside the simple one here:
>
> http://www.objectstyle.org/cayenne/userguide/dataobjects/dataobjects-example.html
>
> Expression e =
> ExpressionFactory.greaterExp("estimatedPrice",
> new BigDecimal(100000.0))
>
> I need to do things with ANDS and ORs and I'm not sure
> how to use expression factory (or should I use
> Expression.fromString() ?) to do it.
>
> Right now my immediate need is to be able to construct
> a query with an arbitary number of possible "and"
> clauses depending on what the user types.
>
> Seems like fromString() is going to be easy and
> powerful but I can't find an example of the syntax
> using google.
>
> Even just a few nice examples would be helpful.
>
> Can I look at the attributes of sub objects using this
> syntax? How?
>
> Thanks!
>
> Eric
>
>
> __________________________________________________
> Do You Yahoo!?
> Tired of spam? Yahoo! Mail has the best spam protection around
> http://mail.yahoo.com
>
--
Joshua T. Pyle
Go has always existed.
RE: Query Examples Needed � Expression.fromString() syntax?
Posted by "Gentry, Michael (Contractor)" <mi...@fanniemae.com>.
Well, if you are fond of BNFs, this might be the best reference:
http://www.objectstyle.org/cayenne/grammar/ExpressionParser.html
It is pretty much the bible for the expression parser. You can look at these wiki pages, too:
http://www.objectstyle.org/confluence/display/CAYDOC/Building+Expressions
http://www.objectstyle.org/confluence/display/CAYDOC/Path+Expressions
There are more pages, of course, but that should give you a good start.
/dev/mrg
-----Original Message-----
From: Eric Lazarus [mailto:ericllazarus@yahoo.com]
Sent: Thursday, May 25, 2006 10:13 AM
To: cayenne-user@incubator.apache.org
Subject: RE: Query Examples Needed � Expression.fromString() syntax?
Oh, that is SO cool! Now I understand why you use
fromString even for UIs.
Thanks for making that clear.
Where do I fnd out about the complete syntax for
Expression.fromString strings?
Is:
http://www.objectstyle.org/confluence/display/CAYDOC/Expressions
http://www.theserverside.com/tt/articles/article.tss?l=Cayenne
the best reference?
What else should I read about this?
Thanks for all your help!
Eric
--- "Gentry, Michael (Contractor)"
<mi...@fanniemae.com> wrote:
> If by a composite data structure you mean joins
> across multiple tables, yes, Cayenne will handle
> that automatically for you based on your definitions
> of the relationships in the modeler. It'll include
> all the tables needed and construct the joins as
> part of the where clause.
>
> I use the fromString() method even for queries
> entered by a user in a web page. Map the text
> fields to hash map entries and fire it off. Cayenne
> figures out what parameters are missing in the map
> and will omit them from the final SQL. This means
> the more text fields the user enters, the more
> specific the query. The less entered, the more
> general the query.
>
> From my example yesterday, if you only have:
>
> expression = Expression.fromString("firstName =
> $firstName and lastName = $lastName");
> parameters.put("lastName", "Gentry");
>
> Then Cayenne will automatically reduce the query
> string to "lastName = $lastName" when you call
> expWithParameters(). (There is a flag to make all
> fields required, though.) So you can write your
> query to be detailed and have sections drop out if
> they aren't needed without changing your query --
> just leave them out of the map. Of course, you can
> glue it together yourself, too. :-)
>
> /dev/mrg
>
>
> -----Original Message-----
> From: Eric Lazarus [mailto:ericllazarus@yahoo.com]
> Sent: Wednesday, May 24, 2006 5:14 PM
> To: cayenne-user@incubator.apache.org
> Subject: RE: Query Examples Needed �
> Expression.fromString() syntax?
>
>
> Oh, I'm not being clear... what I mean is, we will
> end
> up with a composite data structure. I assume that
> Cayenne does the right thing unpacking the composite
> and turning it into one flat "where" clause in the
> eventual sql, right? That's what I meant: am I doing
> the right thing in terms of generating good SQL?
>
> It does seem clear to me that for our case where we
> don't know how many causes there will be until we
> see
> which things the user has filled in, it does seem
> that
> the
>
> e = e.and(...
>
> style will make for pretty simple code.
>
> --- "Gentry, Michael (Contractor)"
> <mi...@fanniemae.com> wrote:
>
> > I don't know which is more efficient as I've never
> > timed them. I'd be willing to wager that your
> > database latency will be significantly higher than
> > having to choose between Expression and
> > ExpressionFactory, though. Perhaps a case of
> trying
> > to optimize too early?
> >
> > I just prefer the way fromString() works so that
> is
> > what I use. It fits my brain better. I believe
> > fromString() appeared in Cayenne 1.1, so before
> that
> > you had to do it the other way (unless I'm just
> > totally off here).
> >
> > Use whichever one feels better to you. :-)
> >
> > /dev/mrg
> >
> >
> > -----Original Message-----
> > From: Eric Lazarus [mailto:ericllazarus@yahoo.com]
>
> > Sent: Wednesday, May 24, 2006 3:45 PM
> > To: cayenne-user@incubator.apache.org
> > Subject: Re: Query Examples Needed �
> > Expression.fromString() syntax?
> >
> >
> > Thank you, Michael and Joshua!
> >
> > What about efficiency? If I want to "and" in a
> bunch
> > of things, like as many as 10 things if the user
> > fills
> > in all the fields of the web query form, then it
> > would
> > look like this? :
> >
> > Expression e =
> > ExpressionFactory.greaterExp("estimatedPrice", new
> > BigDecimal(100000.0));
> >
> > e = e.and(
> > ExpressionFactory.lessExp("estimatedPrice",
> > new
> > BigDecimal(5000.0)) );
> >
> > e = e.and(
> ExpressionFactory.lessExp("productSize",
> > BigDecimal(100.0) );
> >
> > e = e.and(
> > ExpressionFactory.lessExp("productWeight",
> > new
> > BigDecimal(200.0)) );
> >
> > I can just keep appending conditions on like this?
> > Will this turn into efficient SQL code if done
> this
> > way? If not, what is the best way?
> >
> > Thanks,
> >
> > Eric
> >
> > --- Joshua Pyle <jo...@gmail.com> wrote:
> >
> > > I never use fromString any more.
> > >
> > > But using the expressionFactory to and and or
> > > expressions is very simple...
> > >
> > > Expression e =
> > > ExpressionFactory.greaterExp("estimatedPrice",
> new
> > > BigDecimal(100000.0));
> > >
> > > e = e.and(
> > > ExpressionFactory.lessExp("estimatedPrice", new
> > > BigDecimal(5000.0)) );
> > >
> > > --
> > > Joshua T. Pyle
> > > Go has always existed.
> > >
> > > On 5/24/06, Eric Lazarus
> <er...@yahoo.com>
> > > wrote:
> > > > Would anyone reply with some nice examples of
> > > > SelectQuery beside the simple one here:
> > > >
> > > >
> > >
> >
>
http://www.objectstyle.org/cayenne/userguide/dataobjects/dataobjects-example.html
> > > >
> > > > Expression e =
> > > >
> ExpressionFactory.greaterExp("estimatedPrice",
> > > > new
> > BigDecimal(100000.0))
> > > >
> > > > I need to do things with ANDS and ORs and I'm
> > not
> > > sure
> > > > how to use expression factory (or should I use
> > > > Expression.fromString() ?) to do it.
> > > >
> > > > Right now my immediate need is to be able to
> > > construct
> > > > a query with an arbitary number of possible
> > "and"
> > > > clauses depending on what the user types.
> > > >
> > > > Seems like fromString() is going to be easy
> and
> > > > powerful but I can't find an example of the
> > syntax
> > > > using google.
> > > >
> > > > Even just a few nice examples would be
> helpful.
> > > >
> > > > Can I look at the attributes of sub objects
> > using
> > > this
> > > > syntax? How?
> > > >
> > > > Thanks!
> > > >
> > > > Eric
> > > >
> > > >
> > > >
> > __________________________________________________
>
=== message truncated ===
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RE: Query Examples Needed � Expression.fromString() syntax?
Posted by Eric Lazarus <er...@yahoo.com>.
Oh, that is SO cool! Now I understand why you use
fromString even for UIs.
Thanks for making that clear.
Where do I fnd out about the complete syntax for
Expression.fromString strings?
Is:
http://www.objectstyle.org/confluence/display/CAYDOC/Expressions
http://www.theserverside.com/tt/articles/article.tss?l=Cayenne
the best reference?
What else should I read about this?
Thanks for all your help!
Eric
--- "Gentry, Michael (Contractor)"
<mi...@fanniemae.com> wrote:
> If by a composite data structure you mean joins
> across multiple tables, yes, Cayenne will handle
> that automatically for you based on your definitions
> of the relationships in the modeler. It'll include
> all the tables needed and construct the joins as
> part of the where clause.
>
> I use the fromString() method even for queries
> entered by a user in a web page. Map the text
> fields to hash map entries and fire it off. Cayenne
> figures out what parameters are missing in the map
> and will omit them from the final SQL. This means
> the more text fields the user enters, the more
> specific the query. The less entered, the more
> general the query.
>
> From my example yesterday, if you only have:
>
> expression = Expression.fromString("firstName =
> $firstName and lastName = $lastName");
> parameters.put("lastName", "Gentry");
>
> Then Cayenne will automatically reduce the query
> string to "lastName = $lastName" when you call
> expWithParameters(). (There is a flag to make all
> fields required, though.) So you can write your
> query to be detailed and have sections drop out if
> they aren't needed without changing your query --
> just leave them out of the map. Of course, you can
> glue it together yourself, too. :-)
>
> /dev/mrg
>
>
> -----Original Message-----
> From: Eric Lazarus [mailto:ericllazarus@yahoo.com]
> Sent: Wednesday, May 24, 2006 5:14 PM
> To: cayenne-user@incubator.apache.org
> Subject: RE: Query Examples Needed �
> Expression.fromString() syntax?
>
>
> Oh, I'm not being clear... what I mean is, we will
> end
> up with a composite data structure. I assume that
> Cayenne does the right thing unpacking the composite
> and turning it into one flat "where" clause in the
> eventual sql, right? That's what I meant: am I doing
> the right thing in terms of generating good SQL?
>
> It does seem clear to me that for our case where we
> don't know how many causes there will be until we
> see
> which things the user has filled in, it does seem
> that
> the
>
> e = e.and(...
>
> style will make for pretty simple code.
>
> --- "Gentry, Michael (Contractor)"
> <mi...@fanniemae.com> wrote:
>
> > I don't know which is more efficient as I've never
> > timed them. I'd be willing to wager that your
> > database latency will be significantly higher than
> > having to choose between Expression and
> > ExpressionFactory, though. Perhaps a case of
> trying
> > to optimize too early?
> >
> > I just prefer the way fromString() works so that
> is
> > what I use. It fits my brain better. I believe
> > fromString() appeared in Cayenne 1.1, so before
> that
> > you had to do it the other way (unless I'm just
> > totally off here).
> >
> > Use whichever one feels better to you. :-)
> >
> > /dev/mrg
> >
> >
> > -----Original Message-----
> > From: Eric Lazarus [mailto:ericllazarus@yahoo.com]
>
> > Sent: Wednesday, May 24, 2006 3:45 PM
> > To: cayenne-user@incubator.apache.org
> > Subject: Re: Query Examples Needed �
> > Expression.fromString() syntax?
> >
> >
> > Thank you, Michael and Joshua!
> >
> > What about efficiency? If I want to "and" in a
> bunch
> > of things, like as many as 10 things if the user
> > fills
> > in all the fields of the web query form, then it
> > would
> > look like this? :
> >
> > Expression e =
> > ExpressionFactory.greaterExp("estimatedPrice", new
> > BigDecimal(100000.0));
> >
> > e = e.and(
> > ExpressionFactory.lessExp("estimatedPrice",
> > new
> > BigDecimal(5000.0)) );
> >
> > e = e.and(
> ExpressionFactory.lessExp("productSize",
> > BigDecimal(100.0) );
> >
> > e = e.and(
> > ExpressionFactory.lessExp("productWeight",
> > new
> > BigDecimal(200.0)) );
> >
> > I can just keep appending conditions on like this?
> > Will this turn into efficient SQL code if done
> this
> > way? If not, what is the best way?
> >
> > Thanks,
> >
> > Eric
> >
> > --- Joshua Pyle <jo...@gmail.com> wrote:
> >
> > > I never use fromString any more.
> > >
> > > But using the expressionFactory to and and or
> > > expressions is very simple...
> > >
> > > Expression e =
> > > ExpressionFactory.greaterExp("estimatedPrice",
> new
> > > BigDecimal(100000.0));
> > >
> > > e = e.and(
> > > ExpressionFactory.lessExp("estimatedPrice", new
> > > BigDecimal(5000.0)) );
> > >
> > > --
> > > Joshua T. Pyle
> > > Go has always existed.
> > >
> > > On 5/24/06, Eric Lazarus
> <er...@yahoo.com>
> > > wrote:
> > > > Would anyone reply with some nice examples of
> > > > SelectQuery beside the simple one here:
> > > >
> > > >
> > >
> >
>
http://www.objectstyle.org/cayenne/userguide/dataobjects/dataobjects-example.html
> > > >
> > > > Expression e =
> > > >
> ExpressionFactory.greaterExp("estimatedPrice",
> > > > new
> > BigDecimal(100000.0))
> > > >
> > > > I need to do things with ANDS and ORs and I'm
> > not
> > > sure
> > > > how to use expression factory (or should I use
> > > > Expression.fromString() ?) to do it.
> > > >
> > > > Right now my immediate need is to be able to
> > > construct
> > > > a query with an arbitary number of possible
> > "and"
> > > > clauses depending on what the user types.
> > > >
> > > > Seems like fromString() is going to be easy
> and
> > > > powerful but I can't find an example of the
> > syntax
> > > > using google.
> > > >
> > > > Even just a few nice examples would be
> helpful.
> > > >
> > > > Can I look at the attributes of sub objects
> > using
> > > this
> > > > syntax? How?
> > > >
> > > > Thanks!
> > > >
> > > > Eric
> > > >
> > > >
> > > >
> > __________________________________________________
>
=== message truncated ===
__________________________________________________
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Tired of spam? Yahoo! Mail has the best spam protection around
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RE: Query Examples Needed � Expression.fromString() syntax?
Posted by "Gentry, Michael (Contractor)" <mi...@fanniemae.com>.
If by a composite data structure you mean joins across multiple tables, yes, Cayenne will handle that automatically for you based on your definitions of the relationships in the modeler. It'll include all the tables needed and construct the joins as part of the where clause.
I use the fromString() method even for queries entered by a user in a web page. Map the text fields to hash map entries and fire it off. Cayenne figures out what parameters are missing in the map and will omit them from the final SQL. This means the more text fields the user enters, the more specific the query. The less entered, the more general the query.
>From my example yesterday, if you only have:
expression = Expression.fromString("firstName = $firstName and lastName = $lastName");
parameters.put("lastName", "Gentry");
Then Cayenne will automatically reduce the query string to "lastName = $lastName" when you call expWithParameters(). (There is a flag to make all fields required, though.) So you can write your query to be detailed and have sections drop out if they aren't needed without changing your query -- just leave them out of the map. Of course, you can glue it together yourself, too. :-)
/dev/mrg
-----Original Message-----
From: Eric Lazarus [mailto:ericllazarus@yahoo.com]
Sent: Wednesday, May 24, 2006 5:14 PM
To: cayenne-user@incubator.apache.org
Subject: RE: Query Examples Needed � Expression.fromString() syntax?
Oh, I'm not being clear... what I mean is, we will end
up with a composite data structure. I assume that
Cayenne does the right thing unpacking the composite
and turning it into one flat "where" clause in the
eventual sql, right? That's what I meant: am I doing
the right thing in terms of generating good SQL?
It does seem clear to me that for our case where we
don't know how many causes there will be until we see
which things the user has filled in, it does seem that
the
e = e.and(...
style will make for pretty simple code.
--- "Gentry, Michael (Contractor)"
<mi...@fanniemae.com> wrote:
> I don't know which is more efficient as I've never
> timed them. I'd be willing to wager that your
> database latency will be significantly higher than
> having to choose between Expression and
> ExpressionFactory, though. Perhaps a case of trying
> to optimize too early?
>
> I just prefer the way fromString() works so that is
> what I use. It fits my brain better. I believe
> fromString() appeared in Cayenne 1.1, so before that
> you had to do it the other way (unless I'm just
> totally off here).
>
> Use whichever one feels better to you. :-)
>
> /dev/mrg
>
>
> -----Original Message-----
> From: Eric Lazarus [mailto:ericllazarus@yahoo.com]
> Sent: Wednesday, May 24, 2006 3:45 PM
> To: cayenne-user@incubator.apache.org
> Subject: Re: Query Examples Needed �
> Expression.fromString() syntax?
>
>
> Thank you, Michael and Joshua!
>
> What about efficiency? If I want to "and" in a bunch
> of things, like as many as 10 things if the user
> fills
> in all the fields of the web query form, then it
> would
> look like this? :
>
> Expression e =
> ExpressionFactory.greaterExp("estimatedPrice", new
> BigDecimal(100000.0));
>
> e = e.and(
> ExpressionFactory.lessExp("estimatedPrice",
> new
> BigDecimal(5000.0)) );
>
> e = e.and( ExpressionFactory.lessExp("productSize",
> BigDecimal(100.0) );
>
> e = e.and(
> ExpressionFactory.lessExp("productWeight",
> new
> BigDecimal(200.0)) );
>
> I can just keep appending conditions on like this?
> Will this turn into efficient SQL code if done this
> way? If not, what is the best way?
>
> Thanks,
>
> Eric
>
> --- Joshua Pyle <jo...@gmail.com> wrote:
>
> > I never use fromString any more.
> >
> > But using the expressionFactory to and and or
> > expressions is very simple...
> >
> > Expression e =
> > ExpressionFactory.greaterExp("estimatedPrice", new
> > BigDecimal(100000.0));
> >
> > e = e.and(
> > ExpressionFactory.lessExp("estimatedPrice", new
> > BigDecimal(5000.0)) );
> >
> > --
> > Joshua T. Pyle
> > Go has always existed.
> >
> > On 5/24/06, Eric Lazarus <er...@yahoo.com>
> > wrote:
> > > Would anyone reply with some nice examples of
> > > SelectQuery beside the simple one here:
> > >
> > >
> >
>
http://www.objectstyle.org/cayenne/userguide/dataobjects/dataobjects-example.html
> > >
> > > Expression e =
> > > ExpressionFactory.greaterExp("estimatedPrice",
> > > new
> BigDecimal(100000.0))
> > >
> > > I need to do things with ANDS and ORs and I'm
> not
> > sure
> > > how to use expression factory (or should I use
> > > Expression.fromString() ?) to do it.
> > >
> > > Right now my immediate need is to be able to
> > construct
> > > a query with an arbitary number of possible
> "and"
> > > clauses depending on what the user types.
> > >
> > > Seems like fromString() is going to be easy and
> > > powerful but I can't find an example of the
> syntax
> > > using google.
> > >
> > > Even just a few nice examples would be helpful.
> > >
> > > Can I look at the attributes of sub objects
> using
> > this
> > > syntax? How?
> > >
> > > Thanks!
> > >
> > > Eric
> > >
> > >
> > >
> __________________________________________________
> > > Do You Yahoo!?
> > > Tired of spam? Yahoo! Mail has the best spam
> > protection around
> > > http://mail.yahoo.com
> > >
> >
> >
> > --
> > Joshua T. Pyle
> > Go has always existed.
> >
>
>
> __________________________________________________
> Do You Yahoo!?
> Tired of spam? Yahoo! Mail has the best spam
> protection around
> http://mail.yahoo.com
>
__________________________________________________
Do You Yahoo!?
Tired of spam? Yahoo! Mail has the best spam protection around
http://mail.yahoo.com
RE: Query Examples Needed � Expression.fromString() syntax?
Posted by Eric Lazarus <er...@yahoo.com>.
Oh, I'm not being clear... what I mean is, we will end
up with a composite data structure. I assume that
Cayenne does the right thing unpacking the composite
and turning it into one flat "where" clause in the
eventual sql, right? That's what I meant: am I doing
the right thing in terms of generating good SQL?
It does seem clear to me that for our case where we
don't know how many causes there will be until we see
which things the user has filled in, it does seem that
the
e = e.and(...
style will make for pretty simple code.
--- "Gentry, Michael (Contractor)"
<mi...@fanniemae.com> wrote:
> I don't know which is more efficient as I've never
> timed them. I'd be willing to wager that your
> database latency will be significantly higher than
> having to choose between Expression and
> ExpressionFactory, though. Perhaps a case of trying
> to optimize too early?
>
> I just prefer the way fromString() works so that is
> what I use. It fits my brain better. I believe
> fromString() appeared in Cayenne 1.1, so before that
> you had to do it the other way (unless I'm just
> totally off here).
>
> Use whichever one feels better to you. :-)
>
> /dev/mrg
>
>
> -----Original Message-----
> From: Eric Lazarus [mailto:ericllazarus@yahoo.com]
> Sent: Wednesday, May 24, 2006 3:45 PM
> To: cayenne-user@incubator.apache.org
> Subject: Re: Query Examples Needed �
> Expression.fromString() syntax?
>
>
> Thank you, Michael and Joshua!
>
> What about efficiency? If I want to "and" in a bunch
> of things, like as many as 10 things if the user
> fills
> in all the fields of the web query form, then it
> would
> look like this? :
>
> Expression e =
> ExpressionFactory.greaterExp("estimatedPrice", new
> BigDecimal(100000.0));
>
> e = e.and(
> ExpressionFactory.lessExp("estimatedPrice",
> new
> BigDecimal(5000.0)) );
>
> e = e.and( ExpressionFactory.lessExp("productSize",
> BigDecimal(100.0) );
>
> e = e.and(
> ExpressionFactory.lessExp("productWeight",
> new
> BigDecimal(200.0)) );
>
> I can just keep appending conditions on like this?
> Will this turn into efficient SQL code if done this
> way? If not, what is the best way?
>
> Thanks,
>
> Eric
>
> --- Joshua Pyle <jo...@gmail.com> wrote:
>
> > I never use fromString any more.
> >
> > But using the expressionFactory to and and or
> > expressions is very simple...
> >
> > Expression e =
> > ExpressionFactory.greaterExp("estimatedPrice", new
> > BigDecimal(100000.0));
> >
> > e = e.and(
> > ExpressionFactory.lessExp("estimatedPrice", new
> > BigDecimal(5000.0)) );
> >
> > --
> > Joshua T. Pyle
> > Go has always existed.
> >
> > On 5/24/06, Eric Lazarus <er...@yahoo.com>
> > wrote:
> > > Would anyone reply with some nice examples of
> > > SelectQuery beside the simple one here:
> > >
> > >
> >
>
http://www.objectstyle.org/cayenne/userguide/dataobjects/dataobjects-example.html
> > >
> > > Expression e =
> > > ExpressionFactory.greaterExp("estimatedPrice",
> > > new
> BigDecimal(100000.0))
> > >
> > > I need to do things with ANDS and ORs and I'm
> not
> > sure
> > > how to use expression factory (or should I use
> > > Expression.fromString() ?) to do it.
> > >
> > > Right now my immediate need is to be able to
> > construct
> > > a query with an arbitary number of possible
> "and"
> > > clauses depending on what the user types.
> > >
> > > Seems like fromString() is going to be easy and
> > > powerful but I can't find an example of the
> syntax
> > > using google.
> > >
> > > Even just a few nice examples would be helpful.
> > >
> > > Can I look at the attributes of sub objects
> using
> > this
> > > syntax? How?
> > >
> > > Thanks!
> > >
> > > Eric
> > >
> > >
> > >
> __________________________________________________
> > > Do You Yahoo!?
> > > Tired of spam? Yahoo! Mail has the best spam
> > protection around
> > > http://mail.yahoo.com
> > >
> >
> >
> > --
> > Joshua T. Pyle
> > Go has always existed.
> >
>
>
> __________________________________________________
> Do You Yahoo!?
> Tired of spam? Yahoo! Mail has the best spam
> protection around
> http://mail.yahoo.com
>
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RE: Query Examples Needed � Expression.fromString() syntax?
Posted by "Gentry, Michael (Contractor)" <mi...@fanniemae.com>.
I don't know which is more efficient as I've never timed them. I'd be willing to wager that your database latency will be significantly higher than having to choose between Expression and ExpressionFactory, though. Perhaps a case of trying to optimize too early?
I just prefer the way fromString() works so that is what I use. It fits my brain better. I believe fromString() appeared in Cayenne 1.1, so before that you had to do it the other way (unless I'm just totally off here).
Use whichever one feels better to you. :-)
/dev/mrg
-----Original Message-----
From: Eric Lazarus [mailto:ericllazarus@yahoo.com]
Sent: Wednesday, May 24, 2006 3:45 PM
To: cayenne-user@incubator.apache.org
Subject: Re: Query Examples Needed � Expression.fromString() syntax?
Thank you, Michael and Joshua!
What about efficiency? If I want to "and" in a bunch
of things, like as many as 10 things if the user fills
in all the fields of the web query form, then it would
look like this? :
Expression e =
ExpressionFactory.greaterExp("estimatedPrice", new
BigDecimal(100000.0));
e = e.and( ExpressionFactory.lessExp("estimatedPrice",
new
BigDecimal(5000.0)) );
e = e.and( ExpressionFactory.lessExp("productSize",
BigDecimal(100.0) );
e = e.and( ExpressionFactory.lessExp("productWeight",
new
BigDecimal(200.0)) );
I can just keep appending conditions on like this?
Will this turn into efficient SQL code if done this
way? If not, what is the best way?
Thanks,
Eric
--- Joshua Pyle <jo...@gmail.com> wrote:
> I never use fromString any more.
>
> But using the expressionFactory to and and or
> expressions is very simple...
>
> Expression e =
> ExpressionFactory.greaterExp("estimatedPrice", new
> BigDecimal(100000.0));
>
> e = e.and(
> ExpressionFactory.lessExp("estimatedPrice", new
> BigDecimal(5000.0)) );
>
> --
> Joshua T. Pyle
> Go has always existed.
>
> On 5/24/06, Eric Lazarus <er...@yahoo.com>
> wrote:
> > Would anyone reply with some nice examples of
> > SelectQuery beside the simple one here:
> >
> >
>
http://www.objectstyle.org/cayenne/userguide/dataobjects/dataobjects-example.html
> >
> > Expression e =
> > ExpressionFactory.greaterExp("estimatedPrice",
> > new BigDecimal(100000.0))
> >
> > I need to do things with ANDS and ORs and I'm not
> sure
> > how to use expression factory (or should I use
> > Expression.fromString() ?) to do it.
> >
> > Right now my immediate need is to be able to
> construct
> > a query with an arbitary number of possible "and"
> > clauses depending on what the user types.
> >
> > Seems like fromString() is going to be easy and
> > powerful but I can't find an example of the syntax
> > using google.
> >
> > Even just a few nice examples would be helpful.
> >
> > Can I look at the attributes of sub objects using
> this
> > syntax? How?
> >
> > Thanks!
> >
> > Eric
> >
> >
> > __________________________________________________
> > Do You Yahoo!?
> > Tired of spam? Yahoo! Mail has the best spam
> protection around
> > http://mail.yahoo.com
> >
>
>
> --
> Joshua T. Pyle
> Go has always existed.
>
__________________________________________________
Do You Yahoo!?
Tired of spam? Yahoo! Mail has the best spam protection around
http://mail.yahoo.com
Re: Query Examples Needed � Expression.fromString() syntax?
Posted by Eric Lazarus <er...@yahoo.com>.
Thank you, Michael and Joshua!
What about efficiency? If I want to "and" in a bunch
of things, like as many as 10 things if the user fills
in all the fields of the web query form, then it would
look like this? :
Expression e =
ExpressionFactory.greaterExp("estimatedPrice", new
BigDecimal(100000.0));
e = e.and( ExpressionFactory.lessExp("estimatedPrice",
new
BigDecimal(5000.0)) );
e = e.and( ExpressionFactory.lessExp("productSize",
BigDecimal(100.0) );
e = e.and( ExpressionFactory.lessExp("productWeight",
new
BigDecimal(200.0)) );
I can just keep appending conditions on like this?
Will this turn into efficient SQL code if done this
way? If not, what is the best way?
Thanks,
Eric
--- Joshua Pyle <jo...@gmail.com> wrote:
> I never use fromString any more.
>
> But using the expressionFactory to and and or
> expressions is very simple...
>
> Expression e =
> ExpressionFactory.greaterExp("estimatedPrice", new
> BigDecimal(100000.0));
>
> e = e.and(
> ExpressionFactory.lessExp("estimatedPrice", new
> BigDecimal(5000.0)) );
>
> --
> Joshua T. Pyle
> Go has always existed.
>
> On 5/24/06, Eric Lazarus <er...@yahoo.com>
> wrote:
> > Would anyone reply with some nice examples of
> > SelectQuery beside the simple one here:
> >
> >
>
http://www.objectstyle.org/cayenne/userguide/dataobjects/dataobjects-example.html
> >
> > Expression e =
> > ExpressionFactory.greaterExp("estimatedPrice",
> > new BigDecimal(100000.0))
> >
> > I need to do things with ANDS and ORs and I'm not
> sure
> > how to use expression factory (or should I use
> > Expression.fromString() ?) to do it.
> >
> > Right now my immediate need is to be able to
> construct
> > a query with an arbitary number of possible "and"
> > clauses depending on what the user types.
> >
> > Seems like fromString() is going to be easy and
> > powerful but I can't find an example of the syntax
> > using google.
> >
> > Even just a few nice examples would be helpful.
> >
> > Can I look at the attributes of sub objects using
> this
> > syntax? How?
> >
> > Thanks!
> >
> > Eric
> >
> >
> > __________________________________________________
> > Do You Yahoo!?
> > Tired of spam? Yahoo! Mail has the best spam
> protection around
> > http://mail.yahoo.com
> >
>
>
> --
> Joshua T. Pyle
> Go has always existed.
>
__________________________________________________
Do You Yahoo!?
Tired of spam? Yahoo! Mail has the best spam protection around
http://mail.yahoo.com