Problem with ODBC in Windows95 - Database Discussion Boards

gicio12-Jun-02 5:54

12-Jun-02 5:54

I have a fundamental question about
the way .NET handles the object orientated way of
persistence. I am coming from JAVA and WebObjects (Apple)
World and I am looking for a convenient way of working
with objects without seeing any SQL statements only
objects. I have used that approach for years on the
WebObjects Platform (Enterprise Object Framework) and in
Java recently (Container Managed Persistence). I am
looking for something like that in the Microsoft world.

As far as I understand Microsoft does not distinguish
between the Object Model and the Relational Model. The
main difference is that the Object model allows n : m
relationships and the Relational does not allow them. Here
a small example to visualize the problem:

Example:
There is a Patient object with following Attributes

String patientGUID;
String name;
Int age;
Hashtable diseases; (or some other Container like
Collection or Array)

And there is a Disease Object

String diseaseGUID;
String name;

In the object Model there is relation between Patient and
Disease where the patient has his diseases but on the
other site one disease can belong to 1..* patients. (n :
m)

That n : m relationship can not exist within a relational
database without a link table that contains the
connections between the tables: Patient and Disease.

Now, I would like to connect the object Model containing
TWO Entities (Patient, Disease) with the relational
database (containing THREE tables). Then I want to work
with my objects; e.g. create new diseases connect them to
existing patients by putting the diseases into the array
or create new Patients and connect them with already
existing diseases or just change a Patients name. When I
am finished I just want to say SAVECHANGES and the
database is updated accordingly including all link table
entries.

So all I have to care about are my objects and the
relations between them, some invisible layer does all the
dirty work like building SQL, converting the data types
and caching. So if I fetch a Patient with a specified GUID
I do not have to care about fetching his diseases. They
are fetched automatically. If there are too many Diseases
I do not care some kind of algorithm handles that problem
in such a way that if I have to search all of them for
something they are simply there. They are loaded on demand
(lazy evaluation)

Supposing that the disease has a further connection with
some DiseaseType Object/Table and that table has an
attribute/column "Description" I can access it by typing
the following code:

TextField1.Text = currentDisease.type().description()

Please note that to retrieve the description value I did
only fetch the Patient. The diseases and its types were
fetched automatically.

Is something like that possible or am I excepting too much
of the .NET?

Pawel

Re: Can Microsoft beat Apple?

Matt Gullett12-Jun-02 6:24

Matt Gullett

12-Jun-02 6:24

What you are talking about is not a .net feature per-say. What you are looking for is an application server (which is what WebObjects is).

.net can be used to develop an environment like you describe and once it is developed, you can do what you want. However, it does not remove the development aspect of back-end SQL calls, etc.

Re: Can Microsoft beat Apple?

gicio13-Jun-02 4:18

gicio

13-Jun-02 4:18

what I want is:

Object Role Modeling

see my other post!!

Wink | ;)

)))

Pawel

ODBC

12-Jun-02 5:50

Hi,
I am learning C++ and have been doing pretty well until I got to this project I needed to complete. It's just a simple database, nothing fancy. I've imported msado15.dll, and have done eveything by the book but I keep getting this error upon executing the program that says "Data source name not found and no default drive specified. My instructor simply said that some people have an ODBC on thier systems and others don't. If I don't then I wont be able to get this to work. I'd like very much to concentrate on database building and design and was wondering if there is any way around this. I have WinXP Home editiion, and have just gotten (although not installed yet) pro. Any ideas would be appreciated.

I did set up my DSN and just now I did it again thinking that maybe something went wrong the last time. Any other ideas?? Please?

Thanks,
Garry

ADO/MDAC/CDO2000 Memory Leak

[James Pullicino]12-Jun-02 4:51

[James Pullicino]

12-Jun-02 4:51

As posted on MSDN newsgroup:

Hello,

I think that we've stumbled accross a bug in CDO2000 which
causes a massive memory leak. This leaks happens on
Windows 2000 Professional. I failed to reproduce on
Windows 2000 Advanced Server.

Here is the code:

/////
IMessagePtr iMsg ;
iMsg.CreateInstance(__uuidof(Message)) ;

FieldsPtr Flds = iMsg->GetFields() ;
Flds->Item[cdoTo]->Value="james@drinkinginthesun.com";
/////

Is this a known issue? The leak will become obvious if the
above code is thrown into an infite loop. I have tested
this on Windows 2000 Professional with SP2 and Office 2000.

Thanks.

Regards,

James Pullicino

Response from MS:

James,

I see the leak you are reporting. This is apparently a leak in ADO (MDAC),
not CDOSYS. By removing the lines:
FieldsPtr Flds = iMsg->GetFields() ;
Flds->Item[cdoTo]->Value="james@drinkinginthesun.com";

and instead doing:
iMsg->To = "james@drinkingthesun.com";

I eliminated the leak.

Since you can't repro this on your Advanced Server, try comparing the
versions of MDAC on those machines...perhaps that is the difference?

Jason Johnston
Microsoft Developer Support - Messaging

Best Regards,

James Pullicino

Drinking In The Sun
Forgot Password?

System DNS database

Vanting11-Jun-02 3:17

Vanting

11-Jun-02 3:17

Hi,
Is it posible to change a System DSN database path, runtime from a C++ application. Maybe with an API function or??
I have a alias to the System DSN, with this alias I can change the System DNS and by this change the MS Access database connected through the System DSN, but this meens that I need to create a new System DNS for every Access database I use under the application.

Thanks!!
Thomas Vanting

Re: System DNS database

Gethsus13-Jun-02 4:09

Gethsus

13-Jun-02 4:09

Is it necesary to create a System DNS entry for your app, maybe it would be more usefull to create it "on the fly", so you wont have to depend on that fixed path

Problem with ODBC in Windows95

8-Jun-02 22:30

Hi!
I have a project in MFC.In this project i use connection to the Access database (ODBC) and in Windows95 i have a problemm.When i try to connect to database,I recieve the message that driver does not support this function.
i try to install DCOM95 for Windows95
and then Jet40Sp3_Comp for working with Microsoft Access
database (ODBC) from MFC.But during instalation i recieve the
message that Error creating process D:\Win95
\System\odbcconf.exe /e/f
D:\Win95\System\jetodbc.rsp Reason:The system can not find the
file specified.
Tell me,please,is it possible to connect to database with ODBC in Windows95,and if it is possible,what i must do,what drivers or files i must add?!
Thanks,Irina.

Re: Problem with ODBC in Windows95

Mazdak9-Jun-02 3:05

Mazdak

9-Jun-02 3:05

Maybe If you install new version of MDAC it will be ok.

Mazy

"The more I search, the more my need
For you,
The more I bless, the more I bleed
For you."The Outlaw Torn-Metallica

How access Indexing Server with ADO.NET

serberwww5-Jun-02 21:00

serberwww

5-Jun-02 21:00

Hello all.
With ASP/ADO I tried query the Indexing Server of WIndows 2000 server and extract with success many usefull information about files, like Author,Company,Comments,Version ecc. ecc.

Now, how can do this with ADO.NET/ASP.NET.
I have to use a OleDb Provider?

Thanks in advance.

Sergio Bertini

Re: How access Indexing Server with ADO.NET

Sebastian Weber6-Jun-02 2:53

Sebastian Weber

6-Jun-02 2:53

Hi Sergio,

you are right - use the OleDB Provider. Have a look at
http://msdn.microsoft.com/library/en-us/ado270/htm/mdrefindservprovspec.asp?frame=true.

Reagards,
Sebastian

DAO and Visual Studio .Net

5-Jun-02 5:49

Hi!
I can't build with VC++ 7.0 the project that use DAO. The VC++ 6.0 build correctly the same project. I receive the following error message:
fatal error LNK1120: 1 unresolved externals
"public: class ATL::CStringT > > __thiscall CdbLastOLEError::GetDescription(void)"

Do you now somebody the resolution?
Thanks

Feri

ATL7 OLEDB Consumer templates & stored procedures

Jörgen Sigvardsson5-Jun-02 2:35

Jörgen Sigvardsson

5-Jun-02 2:35

I have a consumer template like:

[
    db_command(L"{ ? = CALL dbo.MyProcedure(?) }")
]
class MyProcedure
{
    ...
    [ db_param(1, DBPARAMIO_OUTPUT) ] LONG m_RETURN_VALUE;
    [ db_param(2, DBPARAMIO_INPUT) ] LONG m_id;

    void GetRowsetProperties(CDBPropSet* pPropSet)
    {
         pPropSet->AddProperty(DBPROP_CANFETCHBACKWARDS, true, DBPROPOPTIONS_OPTIONAL);
         pPropSet->AddProperty(DBPROP_CANSCROLLBACKWARDS, true, DBPROPOPTIONS_OPTIONAL);
    }

};

And when I use it I do:

// establish a session to database
storedproc.m_id = someValue;
HRESULT hr = storedproc.Open(session);
// ...check hr
hr = storedproc.MoveFirst();
if(hr == S_OK && storedproc.m_RETURN_VALUE == 0) // retval == 0 is ok
    doSomething();
else
    reportBloodyFailure();

It does not work! MoveFirst returns S_OK, the data from the rowset is in the accessor, but the darn return value is not valid! it's 0xcccccccc which looks an awful lot like uninitialized stack memory... The only two valid return values from this function is 0 or 2 (where 2 is an error code).

Is there anything special I have to do to actually get the return code?

Sonorked as well: 100.13197 jorgen
FreeBSD is sexy.

Searching in a date range with sql

Tim Rymer4-Jun-02 9:14

Tim Rymer

4-Jun-02 9:14

hey, I have a ms access file that stores when an entry was made. if that date field is today, i want to store it in a recordset object. how do i query that?

"SELECT CheckDate WHERE Checkdate = ???? TO ???? "

how would that work??? Please help! Thanks a bunch!

~Timothy T. Rymer

http://tim.xpertz.com
http://www.digipen.edu
http://www.ttrx.com

Re: Searching in a date range with sql

Ed Gadziemski4-Jun-02 13:43

Ed Gadziemski

4-Jun-02 13:43

SELECT CheckDate WHERE CheckDate BETWEEN #??/??/??# AND #??/??/??# should do it.

Re: Searching in a date range with sql

Paul Watson20-Jun-02 2:25

Paul Watson

20-Jun-02 2:25

Ed Gadziemski wrote:
SELECT CheckDate WHERE CheckDate BETWEEN #??/??/??# AND #??/??/??# should do it.

Thanks! I live and learn. Being doing it the hard way all this time Roll eyes | :rolleyes:

FEI: for SQL users replace the hash/pound, #, with a single quote, '. e.g. SELECT CheckDate WHERE CheckDate BETWEEN '??/??/??' AND '??/??/??'

regards,
Paul Watson
Bluegrass
Cape Town, South Africa

The greatest thing you'll ever learn is just to love, and to be loved in return - Moulin Rouge

Tim Smith wrote:
Over here in the third world of humor (a.k.a. BBC America),

peterchen wrote:
We should petition microsoft to a "target=_Paul" attribute.

Is there a way to get the names of the keys that each table has in ADO?

Bart-Man3-Jun-02 11:22

Bart-Man

3-Jun-02 11:22

Greetings,

Is there a way to get the names of the keys that each table has in ADO? I just want to display a each table's keys so that the user can see what keys are available.

Thanks in advance!

Solution to my problem

Bart-Man4-Jun-02 4:22

Bart-Man

4-Jun-02 4:22

Greetings,

I figured it out, all you have to do is the following:

_variant_t p(long(0));
FieldPtr pItem = pRecordset->Fields->GetItem((p)/*_variant_t(&index)*/);
CString szName = (LPCSTR)_bstr_t(pItem->Name);

and this gives you the key name (column heading) for an access database.

How do I get a list of available tables using ADO?

Bart-Man3-Jun-02 8:22

Bart-Man

3-Jun-02 8:22

Greetings,

How do I get a list of available tables using ADO? I am not sure how to do this? I am a newbie to ADO.

Thanks in advance!

Re: How do I get a list of available tables using ADO?

Mazdak3-Jun-02 8:53

Mazdak

3-Jun-02 8:53

I think this article will help you:

Interactive SQL Tool (using ADO)

Mazy

"The more I search, the more my need
For you,
The more I bless, the more I bleed
For you."The Outlaw Torn-Metallica

Re: How do I get a list of available tables using ADO?

Bart-Man3-Jun-02 9:39

Bart-Man

3-Jun-02 9:39

Thanks, that is exactly what I needed! Smile | :)

Re: How do I get a list of available tables using ADO?

Wictor Wilén16-Jun-02 21:19

Wictor Wilén

16-Jun-02 21:19

Heya
Make a "SELECT * FROM sysobjects WHERE xtype = 'U'", this will list all user tables from the database you make this query on.
If you want to list all databases the "SELECT * FROM master.dbo.sysdatabases"

/WW

OLEDB: IRowsetRefresh/IRowsetResync

3-Jun-02 6:43

Can someone give me a working example of one of these two OleDb interfaces? I
need to do a query to the DBMS (SQL Server 2000) and then every X seconds
(where X is customizable) I want to ask to the DBMS if there are
new/modified rows...

Bye
Max

Attributed OLEDB question

Jörgen Sigvardsson3-Jun-02 2:42

Jörgen Sigvardsson

3-Jun-02 2:42

I'm trying to implement simple OLEDB consumer classes for some stored procedures. It turned out that SPs must be attributed in VS.NET.

If I have understood attributes correctly, they are static properties right? So if I have an OLEDB SP like this:

<br />
[<br />
db_source(L"Provider=SQLOLEDB.1;Persist Security Info=False;User ID=sa;Initial Catalog=xxxdb;Data Source=SOMEHOST;Use Procedure for Prepare=1;Auto Translate=True;Packet Size=4096;Workstation ID=SOMEWORKSTATION;Use Encryption for Data=False;Tag with column collation when possible=False"),<br />
	db_command(L"{ ? = CALL dbo.SomeProcedure(?,?,?) }")<br />
]<br />
class CLoadSheetItem<br />
{<br />
public:<br />
 // ...<br />
};<br />

How can I change the Data Source property during runtime? I want this software to be flexible enough so that I can install it and do a simple setup during installation. Is it even possible to change the data source attribute at runtime?

Sonorked as well: 100.13197 jorgen
FreeBSD is sexy.

Re: Attributed OLEDB question

Jörgen Sigvardsson3-Jun-02 2:51

Jörgen Sigvardsson

3-Jun-02 2:51

Nevermind that question.. Smile | :)

Sonorked as well: 100.13197 jorgen
FreeBSD is sexy.

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