ODBC: Microsoft ODBC Database Interface

• Object oriented interface to different databases, part of Win32.
• SQL server, Microsoft Access, foxpro, excel, dbase, paradox, text files.
• Microsoft Foundation Class abstractions on top of ODBC API.
• Insulates you from ODBC directly, presents another model. Based on the design of DAO model, used in Microsoft Access and Visual Basic.
• Microsoft prefers you use their newer MFC based DAO Database Access Objects.
• RFX: Record Field Exchange Architecture
  • Two way transfer of data between database columns and C++ object data members, used with ODBC database classes.
  • RFX is similar to the DFX mechanism in DAO.
  • Custom RFX routines
    • User extension mechanism capabilities:
      • Add new data types, for example, CBookmark.
      • Add new exchange procedures (RFX_???), for example, RFX_Bigint.
      • Have the DoFieldExchange member function conditionally include additional RFX calls or any other valid C++ statements.
    • CMySet::DoFieldExchange(CFieldExchange *pFX)
      • The DoFieldExchange func is much like Serialize. It gets or sets data to or from external form (columns from the result of an ODBC query) from/to member data in the class. The pFX parameter is the context from doing data exchange and is similar to the CArchive parameter to CObject::Serialize. The pFX (a CFieldExchange object) has an operation indicator, which is similar to, but a generalization of the CArchive direction flag. An RFX function may have to support the following operation:
        • BindParam, BindFieldToColumn, Fixup, MarkForAddNew, MarkForUpdate, Name, NameValue, SetFieldDirty, SetFieldNull, IsFieldDirty, IsFieldNull, IsFieldNullable, StoreField, LoadField, GetFieldInfoValue, GetFieldInforOrdinal
      • Recordset field calls are a way of registering memory locations (usually data members) to store field data for a CMySet class.
      • afxdb.h has a list of all the recordset field exchange routines provided with MFC.
      • Recordset exchange field type call:
        • pFX->SetFieldType(CFieldExchange::outputColumn);
      • Each RFX_ function must support various operations, ranging from returning the dirty status of the field to archiving the field in preparation for editing the field.
      • Predefined RFX functions:
        • RFX_LONG, RFX_Int, RFX_Single, RFX_Double, RFX_Text, RFX_Binary, RFX_Date, RFX_LongBinary
      • Recordset exchange function call:
        • RFX_Custom(pFX, "Col2", m_Col2);