The following code shows a sample record that handles commands. In the user record, BEGIN_COLUMN_MAP represents a data rowset passed to the consumer from a provider. BEGIN_PARAM_MAP represents a set of command parameters. This example uses a CCommand class to handle the command parameters. The data members in the map entries represent offsets into one contiguous block of memory for each instance of the class. The COLUMN_ENTRY macros correspond to the PROVIDER_COLUMN_ENTRY macros on the provider side.

For more information about the COLUMN_MAP and PARAM_MAP macros, see Macros for OLE DB Consumer Templates.

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class CArtists { public: // Data Elements CHAR m_szFirstName[20]; CHAR m_szLastName[30]; short m_nAge; // Column binding map BEGIN_COLUMN_MAP(CArtists) COLUMN_ENTRY(1, m_szFirstName) COLUMN_ENTRY(2, m_szLastName) COLUMN_ENTRY(3, m_nAge) END_COLUMN_MAP() // Parameter binding map BEGIN_PARAM_MAP(CArtists) COLUMN_ENTRY(1, m_nAge) END_PARAM_MAP() };

If you use the ATL OLE DB Consumer Wizard to generate a consumer, you have the choice of using OLE DB Templates or OLE DB Attributes. The generated code is different in each case. For more information about this code, see Consumer Wizard-Generated Classes.

For a detailed discussion of the scenarios in which you need to use multiple accessors, see Using Multiple Accessors on a Rowset.

The following example shows the user record modified to support multiple accessors on the rowset. Instead of BEGIN_COLUMN_MAP and END_COLUMN_MAP, it uses BEGIN_ACCESSOR_MAP and BEGIN_ACCESSOR for each accessor. The BEGIN_ACCESSOR macro specifies the accessor number (offset from zero) and whether the accessor is an autoaccessor. Autoaccessors call GetData to retrieve data automatically on a call to MoveNext. Nonautomatic accessors require you to explicitly retrieve the data. Use a nonautomatic accessor if you are binding to a large data field (like a bitmap image) that you might not want to retrieve for every record.

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class CMultiArtists { public: // Data Elements CHAR m_szFirstName[20]; CHAR m_szLastName[30]; short m_nAge; // Column binding map BEGIN_ACCESSOR_MAP(CMultiArtists, 2) BEGIN_ACCESSOR(0, true) // true specifies an auto accessor COLUMN_ENTRY(1, m_szFirstName) COLUMN_ENTRY(2, m_szLastName) END_ACCESSOR() BEGIN_ACCESSOR(1, false) // false specifies a manual accessor COLUMN_ENTRY(3, m_nAge) END_ACCESSOR() END_ACCESSOR_MAP() };

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