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Transfers long integer data between the field data members of a CDaoRecordset object and the columns of a record on the data source.
void AFXAPI DFX_Long( CDaoFieldExchange* pFX, LPCTSTR szName, long& value, DWORD dwBindOptions = AFX_DAO_ENABLE_FIELD_CACHE );
- A pointer to an object of class CDaoFieldExchange. This object contains information to define the context for each call of the function. For more information about the operations a CDaoFieldExchange object can specify, see the article DAO Record Field Exchange: How DFX Works.
- The name of a data column.
- The value stored in the indicated data member — the value to be transferred. For a transfer from recordset to data source, the value, of type long, is taken from the specified data member. For a transfer from data source to recordset, the value is stored in the specified data member.
- An option that lets you take advantage of MFC's double buffering mechanism for detecting recordset fields that have changed. The default, AFX_DAO_ENABLE_FIELD_CACHE, uses double buffering. The other possible value is AFX_DAO_DISABLE_FIELD_CACHE. If you specify this value, MFC does no checking on this field. You must call SetFieldDirty and SetFieldNull yourself.
These options are explained further in the article DAO Recordset: Binding Records Dynamically.
Note You can control whether data is double buffered by default by setting CDaoRecordset::m_bCheckCacheForDirtyFields.
Data is mapped between type DAO_I4 in DAO and type long in the recordset.