DOCUMENT:Q198485  07-MAY-2001  [visualc]
TITLE   :HOWTO: SQL Server 7 Distributed Query Using ATL OLEDB Consumer
PRODUCT :Microsoft C Compiler
PROD/VER:winnt:6.0,7.0
OPER/SYS:
KEYWORDS:kbATL kbDatabase kbDTL kbOLEDB kbSQLServ kbVC600 kbDSupport

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The information in this article applies to:

 - Microsoft Visual C++, 32-bit Enterprise Edition, version 6.0 
 - Microsoft Visual C++, 32-bit Professional Edition, version 6.0 
 - Microsoft Visual C++, 32-bit Learning Edition, version 6.0 
 - Microsoft SQL Server version 7.0 
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SUMMARY
=======

The sample below is an OLE DB Consumer Application that demonstrates how to
perform a distributed query with Visual C++ version 6.0 ATL Consumer templates
to retrieve data from SQL Server (using SQLOLEDB Provider) and Microsoft Access
Database (using Jet OLEDB Provider) by joining the two NorthWind databases.

The application extracts the PRODUCT ID and PRODUCT NAME from a Products table
stored in NorthWind Jet database, joins it with the Products table stored in
NorthWind Microsoft SQL Server 7.0 Database, and applies SQL Server ORDER BY to
sort the final results.

Briefly, create a .cpp file using the code given below in Visual C++ 6.0 and
compile/build from the Build menu (it will prompt for creating a new
workspace--this should build and run without adding new code). Change the
initialization properties to connect to your SQL 7.0 server. In the OpenRoswset
call, change the path to point to NorthWind ("nwind.mdb") sample database on
your machine. The sample database is installed by OLE DB SDK, Access, and Visual
Basic.

MORE INFORMATION
================

Microsoft SQL Server version 7.0 provides the ability to perform queries against
OLE DB providers. This is done by using the OpenQuery or OpenRowset Transact-SQL
functions or by using a query with four-part names including a linked-server
name. For example,

   sp_addlinkedserver 'mylinkedserver', 'product_name', 'myoledbprovider',
   'data_source','location', 'provider_string', 'catalog'

   SELECT * FROM OPENQUERY(mylinkedserver, 'select * from table1')

The SELECT statement performs the SQL statement against the OLE DB Provider.

The following sample code is an OLE DB Consumer Application that uses OLE DB
Consumer Template classes. It uses OpenRowset Transact-SQL function and does not
require a linked server definition.

Sample Code
-----------

      #include <iostream>
      using namespace std ;

      #include <atlbase.h>
      #include <atlimpl.cpp>

      CComModule _Module;
      #define DBINITCONSTANTS

      #include <atlcom.h>
      #include <atldbcli.h>
      #include <msdaguid.h>

      //Accessor Class
      class CProductsAccessor
      {
      public:
         LONG m_ProductID;
         TCHAR m_ProductName[41];

      //output binding map
      BEGIN_COLUMN_MAP(CProductsAccessor)
         COLUMN_ENTRY(1, m_ProductID)
         COLUMN_ENTRY(2, m_ProductName)
      END_COLUMN_MAP()

      };

      void main()
      {
         HRESULT hr ;

         //Initialize COM
         hr = CoInitialize(NULL);

         CDataSource connection ;
         CSession session ;
         CCommand<CAccessor<CProductsAccessor> > product ;

         // Open connection and session
         // ===================================================
         // Setting OLE DB Initialization Properties
         // ===================================================
         CDBPropSet propset(DBPROPSET_DBINIT);
         propset.AddProperty(DBPROP_INIT_DATASOURCE, L"myServer");
         propset.AddProperty(DBPROP_INIT_CATALOG, L"NorthWind");
         propset.AddProperty(DBPROP_AUTH_USERID, L"sa");
         hr = connection.Open("SQLOLEDB", &propset);

         // Open a session.
         hr = session.Open(connection) ;

         // Perform a distributed join using OpenRowset T-SQL function.
         //Note the drive C:\ referenced in the query resides on the server.

         hr = product.Open(session, "select P1.ProductID, P1.ProductName
         from NorthWind..Products P1,
         OpenRowset('Microsoft.Jet.OLEDB.4.0','c:\\Program Files\\Microsoft
            Visual Studio\\VB98\\nwind.mdb';
         'admin';'', 'select ProductID, ProductName from products
         where UnitsInStock between 1 and 5')P2
         where P1.ProductID = P2.ProductID order by P1.ProductName");

         //Get data from the rowset.
         while(product.MoveNext() == S_OK)
         {
            cout << product.m_ProductID << " ";
            cout << product.m_ProductName << endl ;
         }
      }

REFERENCES
==========

For more details on setting up and using Distributed Queries, please see
"sp_addlinkedserver", "OpenQuery", "OpenRowset", and related topics in SQL
Server 7.0 Books Online.

To learn more about the Accessor used in the code above, run the ATL Consumer
Wizard on SQL Server 7 NorthWind database, Products Table.

For additional information that describes the requirements to add OLE DB template
support to Visual C++ projects, please see the following article in the
Microsoft Knowledge Base:

   Q190959 PRB: OLE DB Consumer Template Wizard Requires ATL Project

For additional information, see the Support WebCast at the following location:

   http://support.microsoft.com/servicedesks/webcasts/wc102699/WC102699.asp

Additional query words:

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Keywords          : kbATL kbDatabase kbDTL kbOLEDB kbSQLServ kbVC600 kbDSupport 
Technology        : kbVCsearch kbSQLServSearch kbAudDeveloper kbSQLServ700 kbVC600 kbVC32bitSearch
Version           : winnt:6.0,7.0
Issue type        : kbhowto

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