Storing Strings in the OLE DB Provider

 

The latest version of this topic can be found at Storing Strings in the OLE DB Provider.

In MyProviderRS.h, the ATL OLE DB Provider Wizard creates a default user record called CWindowsFile. To handle the two strings, either modify CWindowsFile or add your own user record as shown in the following code:

////////////////////////////////////////////////////////////////////////  
class CAgentMan:   
   public WIN32_FIND_DATA  
   DWORD dwBookmark;              // Add this  
   TCHAR szCommand[256];          // Add this  
   TCHAR szText[256];             // Add this  
   TCHAR szCommand2[256];         // Add this  
   TCHAR szText2[256];            // Add this  
  
{  
public:  
BEGIN_PROVIDER_COLUMN_MAP()  
   PROVIDER_COLUMN_ENTRY_STR(OLESTR("Command"), 1, 256, GUID_NULL, CAgentMan, szCommand)  
   PROVIDER_COLUMN_ENTRY_STR(OLESTR("Text"), 2, 256, GUID_NULL, CAgentMan, szText)   
   PROVIDER_COLUMN_ENTRY_STR(OLESTR("Command2"), 3, 256, GUID_NULL, CAgentMan, szCommand2)  
   PROVIDER_COLUMN_ENTRY_STR(OLESTR("Text2"),4, 256, GUID_NULL, CAgentMan, szText2)  
END_PROVIDER_COLUMN_MAP()  
   bool operator==(const CAgentMan& am) // This is optional   
   {  
      return (lstrcmpi(cFileName, wf.cFileName) == 0);  
   }  
};  

The data members szCommand and szText represent the two strings, with szCommand2 and szText2 providing additional columns if needed. The data member dwBookmark is not needed for this simple read-only provider but is used later to add an IRowsetLocate interface; see Enhancing the Simple Read Only Provider. The == operator compares instances (implementing this operator is optional).

When this is done, your provider should be ready to compile and run. To test the provider, you need a consumer with matching functionality. Implementing a Simple Consumer shows how to create such a test consumer. Run the test consumer with the provider. Verify that the test consumer retrieves the proper strings from the provider when you click the Run button in the Test Consumer dialog box.

When you have successfully tested your provider, you might want to enhance its functionality by implementing additional interfaces. An example is shown in Enhancing the Simple Read-Only Provider.

See Also

Implementing the Simple Read-Only Provider