Populating and scrolling the Listbox using query

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Populating and scrolling the Listbox using query

Farzana
Dear All,

We are working in eVC++ environment with SQLite database.We need to populate the listbox with the values obtained by executing the query.
We were able to get the values of the query by using the API’s sqlite3_prepare and sqlite3_step.
But we were able to populate and move the listbox in the downward direction only and we couldn’t get the correct result when we click the upward direction button of the listbox.Is there any API or functions available to move the data in upward direction in the listbox?

We happened to come across the functions of BTree such as sqlite3BtreePrevious, sqlite3BtreeNext where we are suppose to use cursors. Is it possible to execute the query using cursors and move the pointer in the upward or downward direction?

Kindly help in this regard.
Thanks in advance.

Regards,
Farzana.
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Re: Populating and scrolling the Listbox using query

Igor Tandetnik
"Farzana" <[hidden email]>
wrote in message news:[hidden email]
> We are working in eVC++ environment with SQLite database.We need to
> populate the listbox with the values obtained by executing the query.
> We were able to get the values of the query by using the API's
> sqlite3_prepare and sqlite3_step.
> But we were able to populate and move the listbox in the downward
> direction only

http://www.sqlite.org/cvstrac/wiki?p=ScrollingCursor

Igor Tandetnik



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Re: Populating and scrolling the Listbox using query

Fred Williams
Might want to download the free source for the Delphi VCL set for Sqlite DB
access componenets provided at Aducom.com and review the releven source
code. Sorry, it is written that highly "inelegant" Object Pascal.  But I'm
an old "C" coder from way back and do read and write Object Pascal more so
than "C".  Just think of it as a wordy "C" without a real need for those
pesky pointers.  I have never looked that deep in that particular area of
the source so have no direct suggestions.  I just let Delphi VCL's do the
scrolling in either direction.

Fred

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]]On Behalf Of Igor Tandetnik
Sent: Monday, April 14, 2008 6:36 AM
To: [hidden email]
Subject: Re: [sqlite] Populating and scrolling the Listbox using query


"Farzana" <[hidden email]>
wrote in message news:[hidden email]
> We are working in eVC++ environment with SQLite database.We need to
> populate the listbox with the values obtained by executing the query.
> We were able to get the values of the query by using the API's
> sqlite3_prepare and sqlite3_step.
> But we were able to populate and move the listbox in the downward
> direction only

http://www.sqlite.org/cvstrac/wiki?p=ScrollingCursor

Igor Tandetnik



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Re: Populating and scrolling the Listbox using query

Clay Dowling
In reply to this post by Farzana
Farzana wrote:

> Dear All,
>
> We are working in eVC++ environment with SQLite database.We need to populate
> the listbox with the values obtained by executing the query.
> We were able to get the values of the query by using the API’s
> sqlite3_prepare and sqlite3_step.
> But we were able to populate and move the listbox in the downward direction
> only and we couldn’t get the correct result when we click the upward
> direction button of the listbox.Is there any API or functions available to
> move the data in upward direction in the listbox?
>
> We happened to come across the functions of BTree such as
> sqlite3BtreePrevious, sqlite3BtreeNext where we are suppose to use cursors.
> Is it possible to execute the query using cursors and move the pointer in
> the upward or downward direction?

Farzana,

Moving the list control has nothing to do with SQLite, that's a function
of your interface code.  I have a couple of solutions that I use for
dealing with grids and list controls in general.

The first is to maintain a shadow store behind the scenes with the data
from my database records.  In particular, I define a class to hold a
record.  My screen has a vector of these classes.  So when the user
makes changes to row 3 of the list control, behind the scenes I make
those changes to item 3 of the vector.  In fact I find this easiest to
do by deriving a specialized list control that deals with this
particular view on the data.

Another approach is to record the primary key with each row of the list
control.  This works fine if you don't allow in-place editing, and the
users will only be adding or deleting records (or their edits occur on a
different screen).

Clay

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Re: Populating and scrolling the Listbox using query

Farzana
In reply to this post by Igor Tandetnik
Thanks for your reply Igor.

We tried populating the listbox as mentioned in the URL.We are successful in populating the listbox but when we go for scrolling the data, it takes more time to move forward and backward since it has to execute the query everytime. We are using a PocketPc so it is much slower. Is there any other way to do this or can some one provide us a sample code for the same.
We are using a Table say Employees where we have to dsiplay their Job Description in ascending order in a user defined listbox with scroll up and scroll down buttons. Can anyone provide us a suggestion.
Thanks in Advance.

Regards,
Farzana


Igor Tandetnik wrote
"Farzana" <hussainfarzana.k@dexterity.in>
wrote in message news:16676178.post@talk.nabble.com
> We are working in eVC++ environment with SQLite database.We need to
> populate the listbox with the values obtained by executing the query.
> We were able to get the values of the query by using the API's
> sqlite3_prepare and sqlite3_step.
> But we were able to populate and move the listbox in the downward
> direction only

http://www.sqlite.org/cvstrac/wiki?p=ScrollingCursor

Igor Tandetnik



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Re: Populating and scrolling the Listbox using query

Eric Pankoke
In reply to this post by Farzana
Is it possible to store all of the needed data in memory?  If so, why not read the required information into an array and just update an index variable to keep track of where you are at in the array when the user clicks the up and down buttons?  That should be quite fast.

--
Eric Pankoke
Founder / Lead Developer
Point Of Light Software
http://www.polsoftware.com/

 -------------- Original message ----------------------
From: Farzana <[hidden email]>

>
> Thanks for your reply Igor.
>
> We tried populating the listbox as mentioned in the URL.We are successful in
> populating the listbox but when we go for scrolling the data, it takes more
> time to move forward and backward since it has to execute the query
> everytime. We are using a PocketPc so it is much slower. Is there any other
> way to do this or can some one provide us a sample code for the same.
> We are using a Table say Employees where we have to dsiplay their Job
> Description in ascending order in a user defined listbox with scroll up and
> scroll down buttons. Can anyone provide us a suggestion.
> Thanks in Advance.
>
> Regards,
> Farzana
>
>
>
> Igor Tandetnik wrote:
> >
> > "Farzana" <[hidden email]>
> > wrote in message news:[hidden email]
> >> We are working in eVC++ environment with SQLite database.We need to
> >> populate the listbox with the values obtained by executing the query.
> >> We were able to get the values of the query by using the API's
> >> sqlite3_prepare and sqlite3_step.
> >> But we were able to populate and move the listbox in the downward
> >> direction only
> >
> > http://www.sqlite.org/cvstrac/wiki?p=ScrollingCursor
> >
> > Igor Tandetnik
> >
> >
> >
> > _______________________________________________
> > sqlite-users mailing list
> > [hidden email]
> > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
> >
> >
>
> --
> View this message in context:
> http://www.nabble.com/Populating-and-scrolling-the-Listbox-using-query-tp1667617
> 8p16806114.html
> Sent from the SQLite mailing list archive at Nabble.com.
>
> _______________________________________________
> sqlite-users mailing list
> [hidden email]
> http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users

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Re: Populating and scrolling the Listbox using query

Farzana
Thanks for the quick reply Epankoke.
We tried as you mentioned. But we are restricted with the memory size and the storage of the needed data occupies some MB's of space in the memory so we cannot go for it. Is there any other work around to perform the scrolling condition.

Kindly help in this regard.

Regards,
Farzana.

epankoke wrote
Is it possible to store all of the needed data in memory?  If so, why not read the required information into an array and just update an index variable to keep track of where you are at in the array when the user clicks the up and down buttons?  That should be quite fast.

--
Eric Pankoke
Founder / Lead Developer
Point Of Light Software
http://www.polsoftware.com/

 -------------- Original message ----------------------
From: Farzana <hussainfarzana.k@dexterity.in>
>
> Thanks for your reply Igor.
>
> We tried populating the listbox as mentioned in the URL.We are successful in
> populating the listbox but when we go for scrolling the data, it takes more
> time to move forward and backward since it has to execute the query
> everytime. We are using a PocketPc so it is much slower. Is there any other
> way to do this or can some one provide us a sample code for the same.
> We are using a Table say Employees where we have to dsiplay their Job
> Description in ascending order in a user defined listbox with scroll up and
> scroll down buttons. Can anyone provide us a suggestion.
> Thanks in Advance.
>
> Regards,
> Farzana
>
>
>
> Igor Tandetnik wrote:
> >
> > "Farzana" <hussainfarzana.k@dexterity.in>
> > wrote in message news:16676178.post@talk.nabble.com
> >> We are working in eVC++ environment with SQLite database.We need to
> >> populate the listbox with the values obtained by executing the query.
> >> We were able to get the values of the query by using the API's
> >> sqlite3_prepare and sqlite3_step.
> >> But we were able to populate and move the listbox in the downward
> >> direction only
> >
> > http://www.sqlite.org/cvstrac/wiki?p=ScrollingCursor
> >
> > Igor Tandetnik
> >
> >
> >
> > _______________________________________________
> > sqlite-users mailing list
> > sqlite-users@sqlite.org
> > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
> >
> >
>
> --
> View this message in context:
> http://www.nabble.com/Populating-and-scrolling-the-Listbox-using-query-tp1667617
> 8p16806114.html
> Sent from the SQLite mailing list archive at Nabble.com.
>
> _______________________________________________
> sqlite-users mailing list
> sqlite-users@sqlite.org
> http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users

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Re: Populating and scrolling the Listbox using query

Neville Franks-3
Tuesday, April 22, 2008, 2:52:37 PM, you wrote:

Why not just keep the rowid's in an array and query the actual row
contents as needed. This is typical with virtual list or tree
controls. That is you keep a reference to the data, not the data
itself.


F> Thanks for the quick reply Epankoke.
F> We tried as you mentioned. But we are restricted with the memory size and
F> the storage of the needed data occupies some MB's of space in the memory so
F> we cannot go for it. Is there any other work around to perform the scrolling
F> condition.

F> Kindly help in this regard.

F> Regards,
F> Farzana.


F> epankoke wrote:

>>
>> Is it possible to store all of the needed data in memory?  If so, why not
>> read the required information into an array and just update an index
>> variable to keep track of where you are at in the array when the user
>> clicks the up and down buttons?  That should be quite fast.
>>
>> --
>> Eric Pankoke
>> Founder / Lead Developer
>> Point Of Light Software
>> http://www.polsoftware.com/
>>
>>  -------------- Original message ----------------------
>> From: Farzana <[hidden email]>
>>>
>>> Thanks for your reply Igor.
>>>
>>> We tried populating the listbox as mentioned in the URL.We are successful
>>> in
>>> populating the listbox but when we go for scrolling the data, it takes
>>> more
>>> time to move forward and backward since it has to execute the query
>>> everytime. We are using a PocketPc so it is much slower. Is there any
>>> other
>>> way to do this or can some one provide us a sample code for the same.
>>> We are using a Table say Employees where we have to dsiplay their Job
>>> Description in ascending order in a user defined listbox with scroll up
>>> and
>>> scroll down buttons. Can anyone provide us a suggestion.
>>> Thanks in Advance.
>>>
>>> Regards,
>>> Farzana
>>>
>>>
>>>
>>> Igor Tandetnik wrote:
>>> >
>>> > "Farzana" <[hidden email]>
>>> > wrote in message news:[hidden email]
>>> >> We are working in eVC++ environment with SQLite database.We need to
>>> >> populate the listbox with the values obtained by executing the query.
>>> >> We were able to get the values of the query by using the API's
>>> >> sqlite3_prepare and sqlite3_step.
>>> >> But we were able to populate and move the listbox in the downward
>>> >> direction only
>>> >
>>> > http://www.sqlite.org/cvstrac/wiki?p=ScrollingCursor
>>> >
>>> > Igor Tandetnik
>>> >
>>> >
>>> >
>>> > _______________________________________________
>>> > sqlite-users mailing list
>>> > [hidden email]
>>> > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
>>> >
>>> >
>>>
>>> --
>>> View this message in context:
>>> http://www.nabble.com/Populating-and-scrolling-the-Listbox-using-query-tp1667617
>>> 8p16806114.html
>>> Sent from the SQLite mailing list archive at Nabble.com.
>>>
>>> _______________________________________________
>>> sqlite-users mailing list
>>> [hidden email]
>>> http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
>>
>> _______________________________________________
>> sqlite-users mailing list
>> [hidden email]
>> http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
>>
>>



--
Best regards,
  Neville Franks, http://www.surfulater.com http://blog.surfulater.com
 

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Re: Populating and scrolling the Listbox using query

Eric Pankoke
That seems like it would cut down on some of your query times.  When you
say it's running slow, how slow are you talking about?

Eric Pankoke
Founder
Point Of Light Software
http://www.polsoftware.com/
 
-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Neville Franks
Sent: Tuesday, April 22, 2008 1:08 AM
To: General Discussion of SQLite Database
Subject: Re: [sqlite] Populating and scrolling the Listbox using query

Tuesday, April 22, 2008, 2:52:37 PM, you wrote:

Why not just keep the rowid's in an array and query the actual row
contents as needed. This is typical with virtual list or tree
controls. That is you keep a reference to the data, not the data
itself.


F> Thanks for the quick reply Epankoke.
F> We tried as you mentioned. But we are restricted with the memory size
and
F> the storage of the needed data occupies some MB's of space in the
memory so
F> we cannot go for it. Is there any other work around to perform the
scrolling
F> condition.

F> Kindly help in this regard.

F> Regards,
F> Farzana.


F> epankoke wrote:
>>
>> Is it possible to store all of the needed data in memory?  If so, why
not

>> read the required information into an array and just update an index
>> variable to keep track of where you are at in the array when the user
>> clicks the up and down buttons?  That should be quite fast.
>>
>> --
>> Eric Pankoke
>> Founder / Lead Developer
>> Point Of Light Software
>> http://www.polsoftware.com/
>>
>>  -------------- Original message ----------------------
>> From: Farzana <[hidden email]>
>>>
>>> Thanks for your reply Igor.
>>>
>>> We tried populating the listbox as mentioned in the URL.We are
successful
>>> in
>>> populating the listbox but when we go for scrolling the data, it
takes
>>> more
>>> time to move forward and backward since it has to execute the query
>>> everytime. We are using a PocketPc so it is much slower. Is there
any
>>> other
>>> way to do this or can some one provide us a sample code for the
same.
>>> We are using a Table say Employees where we have to dsiplay their
Job
>>> Description in ascending order in a user defined listbox with scroll
up

>>> and
>>> scroll down buttons. Can anyone provide us a suggestion.
>>> Thanks in Advance.
>>>
>>> Regards,
>>> Farzana
>>>
>>>
>>>
>>> Igor Tandetnik wrote:
>>> >
>>> > "Farzana" <[hidden email]>
>>> > wrote in message news:[hidden email]
>>> >> We are working in eVC++ environment with SQLite database.We need
to
>>> >> populate the listbox with the values obtained by executing the
query.

>>> >> We were able to get the values of the query by using the API's
>>> >> sqlite3_prepare and sqlite3_step.
>>> >> But we were able to populate and move the listbox in the downward
>>> >> direction only
>>> >
>>> > http://www.sqlite.org/cvstrac/wiki?p=ScrollingCursor
>>> >
>>> > Igor Tandetnik
>>> >
>>> >
>>> >
>>> > _______________________________________________
>>> > sqlite-users mailing list
>>> > [hidden email]
>>> > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
>>> >
>>> >
>>>
>>> --
>>> View this message in context:
>>>
http://www.nabble.com/Populating-and-scrolling-the-Listbox-using-query-t
p1667617

>>> 8p16806114.html
>>> Sent from the SQLite mailing list archive at Nabble.com.
>>>
>>> _______________________________________________
>>> sqlite-users mailing list
>>> [hidden email]
>>> http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
>>
>> _______________________________________________
>> sqlite-users mailing list
>> [hidden email]
>> http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
>>
>>



--
Best regards,
  Neville Franks, http://www.surfulater.com http://blog.surfulater.com
 

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