CDaoFieldExchange::m_nOperation

Identifies the operation to be performed on the CDaoRecordset object associated with the field exchange object.

Remarks

The CDaoFieldExchange object supplies the context for a number of different DFX operations on the recordset.

注意

The PSEUDO NULL value described under the MarkForAddNew and SetFieldNull operations below is a value used to mark fields Null. The DAO record field exchange mechanism (DFX) uses this value to determine which fields have been explicitly marked Null. PSEUDO NULL is not required for COleDateTime and COleCurrency fields.

Possible values of m_nOperation are:

Operation	Description
AddToParameterList	Builds the PARAMETERS clause of the SQL statement.
AddToSelectList	Builds the SELECT clause of the SQL statement.
BindField	Binds a field in the database to a memory location in your application.
BindParam	Sets parameter values for the recordset's query.
Fixup	Sets the Null status for a field.
AllocCache	Allocates the cache used to check for "dirty" fields in the recordset.
StoreField	Saves the current record to the cache.
LoadField	Restores the cached data member variables in the recordset.
FreeCache	Frees the cache used to check for "dirty" fields in the recordset.
SetFieldNull	Sets a field's status to Null and value to PSEUDO NULL.
MarkForAddNew	Marks fields "dirty" if not PSEUDO NULL.
MarkForEdit	Marks fields "dirty" if they do not match the cache.
SetDirtyField	Sets field values marked as "dirty."
DumpField	Dumps a field's contents (debug only).
MaxDFXOperation	Used for input checking.

Requirements

Header: afxdao.h

See Also

Reference

CDaoFieldExchange Class

Hierarchy Chart

CDaoFieldExchange::IsValidOperation

CDaoFieldExchange::m_prs

CDaoRecordset::DoFieldExchange

Other Resources

CDaoFieldExchange Members