Using Bookmarks

Before you open the rowset, you must tell the provider that you want to use bookmarks. To do this, set the DBPROP_BOOKMARKS property to true in your property set. The provider retrieves bookmarks as column zero, so you must use the special macro BOOKMARK_ENTRY and the CBookmark class if you are using a static accessor. CBookmark is a template class where the argument is the length in bytes of the bookmark buffer. The length of the buffer required for a bookmark depends on the provider. If you are using the ODBC OLE DB provider, as shown in the following example, the buffer must be 4 bytes.

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class CProducts { public: CBookmark<4> bookmark; BEGIN_COLUMN_MAP(CProducts) BOOKMARK_ENTRY(bookmark) END_COLUMN_MAP() }; CDBPropSet propset(DBPROPSET_ROWSET); propset.AddProperty(DBPROP_BOOKMARKS, true); CTable<CAccessor<CProducts> > product; product.Open(session, "Products", &propset);

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class CProducts
{
public:
   CBookmark<4>   bookmark;

   BEGIN_COLUMN_MAP(CProducts)
      BOOKMARK_ENTRY(bookmark)
   END_COLUMN_MAP()
};

CDBPropSet propset(DBPROPSET_ROWSET);
propset.AddProperty(DBPROP_BOOKMARKS, true);

CTable<CAccessor<CProducts> > product;
product.Open(session, "Products", &propset);

If you use CDynamicAccessor, the buffer is dynamically allocated at run time. In this case, you can use a specialized version of CBookmark for which you do not specify a buffer length. Use the function GetBookmark to retrieve the bookmark from the current record, as shown in this code sample:

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CTable<CDynamicAccessor> product; CBookmark<> bookmark; CDBPropSet propset(DBPROPSET_ROWSET); propset.AddProperty(DBPROP_BOOKMARKS, true); product.Open(session, "Products", &propset); product.MoveNext(); product.GetBookmark(&bookmark);

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CTable<CDynamicAccessor> product;
CBookmark<>              bookmark;
CDBPropSet propset(DBPROPSET_ROWSET);

propset.AddProperty(DBPROP_BOOKMARKS, true);
product.Open(session, "Products", &propset);
product.MoveNext();
product.GetBookmark(&bookmark);

For information about supporting bookmarks in providers, see Provider Support for Bookmarks.

See Also

Concepts