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ADO Wrapper Classes

Posted by Dogu Tumerdem on March 21st, 2001

Environment: VC6 SP4, NT4 SP6

Acknowledgements

This article is based in part on Bob Place's ADO is AOK (a simple ADO tutorial).

Wrapper Usage

This is consist of 2 classes.
  • CDyndb : This Class manages connections and recordsets. Recordsets are organized as linked list (CList) and you can access them using their ids.
  • CDynRec : This class is the node to populate for each recordsets.
Simply follow these steps in order to use the ADO wrapper classes:
  1. You need to add the following line stdafx.h :
    2. #import "c:\program files\common files\system\ado\msado21.tlb" no_namespace rename ("EOF", "adoEOF")
  2. Call the OpenConn function 
    theApp.m_dyndb.OpenConn("driver=sql server;server=dogu;UID=sa;PWD=;database=dbtraining;");
  3. Call OpenRec function 
    4. theApp.m_dyndb.OpenRec("select * from Courses");
  4. Call GetFieldVal function to get the value of the fields. This function returns variant type. You can cast it as usual way like "short(variantdata);" 
    5. vardat=theApp.m_dyndb.GetFieldVal(0,2);
  5. Call GetFieldType to get the type of the field. "en" has a definition like DataTypeEnum en; (see MSDN for details)
    6. en=theApp.m_dyndb.GetFieldType(0,2);
  6. Call GetFieldCount to get the number of the fields that selected in the recordset.

  7. Call GetFieldName to obtain the name of the field.
To iterate through a recordset, you can use the m_pRecordSet member functions MoveXXX.

Downloads

Download source - 2 Kb
Download demo project - 121 Kb

IT Offers

Comments

  • This is not working.

    Posted by Haranadh on 02/28/2006 04:27am 

    I tried to execute the demo project. but it is not executing. why? check once.

    Reply

  • Recordset Navigator and Count

    Posted by Legacy on 02/22/2002 12:00am

    Originally posted by: Doug Hagerman 

    I can now get the field values.


    However, I tried implementing a MoveNext Function to navigator the recordset, and although it didn't crash, it didn't seem to moveNext


    //.h File

    	void MoveNext();


    //.ccp File

    void CDyndb::MoveNext()

    {

    	m_pRecordset->MoveNext;

    }


    

    //Code:


    //In the Command Button


    for(int i=0;i<5;i++) 

    {

    ret=(char*)_bstr_t(theApp.m_dyndb.GetFieldVal(0,"Company_Name"));

    m_List.AddString(ret);

    theApp.m_dyndb.MoveNext();

    }

    ////////////////////////////////////////////////////////

    The Warning During Compiling is:

    --------------------Configuration: AdoTest - Win32 Debug--------------------

    Compiling...

    Dyndb.cpp

    \\Blackpanther\Source_Code\VC\AdoWrapper\Dyndb.cpp(215) : warning C4551: function call missing argument list

    Linking...


    AdoTest.exe - 0 error(s), 1 warning(s)

    ///////////////////////////////////////////////////////////

    What is the Argument List?

    ///////////////////////////////////////////////////////////

    I tried adding

    //.ccp File

    void CDyndb::MoveNext()

    {

    	m_pRecordset->MoveNext();

    }

    the () to the end of move next and although it eliminates the compile warning it crashed with Abnormal Program Termination

    ///////////////////////////////////////////////////////////

    So Next I tried

    void CDyndb::MoveNext()

    {

    	//m_pRecordset->MoveNext();

    	CDynRec temprec;

    	temprec.m_pRecordset->MoveNext();

    }

    and it still gives 

    Abnormal Program Termination

    and crashes

    ////////////////////////////////////////////////////////////


    Also, the record count give me over 4 million records when there is just over 1000?


    CString a;

    a.Format("Record Count=%d",theApp.m_dyndb.GetRecCount);

    AfxMessageBox(a);

    ////////////////////////////////////////////////////

    After further research the RecordCount is always 4,199,165

    This seems strange

    ////////////////////////////////////////////////////


    Thanks for your previous help.

    Doug

    Reply

  • IT Manager

    Posted by Legacy on 02/21/2002 12:00am

    Originally posted by: Doug Hagerman 

    I have used this example in for ADO wrapper in C and the GetFieldCount, GetFieldType work but I also get a Run Time Error that says abnormal program termination.


    How do I get a Company_Name for instance into a string variable so I can use the data from the Recordset?


    In the # 4 Example I don't understand how to define the following:


    "short(variantdata);" 

    vardat=theApp.m_dyndb.GetFieldVal(0,2);


    


    So Here was one attempt that cause a crash:


    	short(variantdata) vardat;

    	vardat= theApp.m_dyndb.GetFieldVal(0,"Companies");

    	//a.Format("FV=%s",vardat);

    	AfxMessageBox(vardat); I also tried (a) in the Afx


    or

    	short vardat;

    	vardat= theApp.m_dyndb.GetFieldVal(0,"Companies");

    	//a.Format("FV=%s",vardat);

    	AfxMessageBox(vardat); I also tried (a) in the Afx


    or


    	short(variantdata) vardat;

    	vardat= theApp.m_dyndb.GetFieldVal(0,2);

    	//a.Format("FV=%s",vardat);

    	AfxMessageBox(vardat); I also tried (a) in the Afx


    So what am I doing wrong?


    Also, how do you count the # of records in a Record Set?


    


    Please Help,

    Doug

    Reply

  • Problem

    Posted by Legacy on 04/12/2001 12:00am

    Originally posted by: zhouhao

    I think the #import will cause problem some times because the .dll or tlb file will be installed somewhere instead of c:\program\common files\... so that you need to recompile your program before you distribute it. Is there any other way to overcome this problem?

    Reply

  • All Fixed...

    Posted by Legacy on 04/10/2001 12:00am

    Originally posted by: Dogu Tumerdem

    download new version from :

    http://freedrive.com
    user : dogutumerdem
    pass : humankind

    dyndb.zip

    Reply

  • Some Bugs !

    Posted by Legacy on 03/22/2001 12:00am

    Originally posted by: Anonymous

    After modifying button one to point to my database, table, and sa password, i got the About box's Button1 to display the message box(es) ok. But after i close the About box and then File->Exit the application I get ...

    ADOTEST caused an invalid page fault in
    module OLEDB32.DLL at 0167:1f9c7567.
    Registers:
    EAX=00000000 CS=0167 EIP=1f9c7567 EFLGS=00210246
    EBX=011b7188 SS=016f ESP=0065fa70 EBP=0065facc
    ECX=00000000 DS=016f ESI=00000000 FS=3dbf
    EDX=bffc9490 ES=016f EDI=00000000 GS=0000
    Bytes at CS:EIP:
    8b 77 08 8d 46 04 50 ff 15 08 11 9c 1f ff 46 1c
    Stack dump:
    00000000 00000000 1f9ce482 bff7438c 00000000 0065facc 011b7188 1f9ce46d 011b0728 1f9ca4b3 00000000 011b0728 00000000 011b0728 011b7188 011b4464

    I was ADO curious but not ADO employeed so I haven't spent any time debugging this.

    Just an FYI...

    Reply
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