次の方法で共有


CRecordset::IsBOF

Returns nonzero if the recordset has been positioned before the first record. There is no current record.

BOOL IsBOF( ) const;

Return Value

Nonzero if the recordset contains no records or if you have scrolled backward before the first record; otherwise 0.

Remarks

Call this member function before you scroll from record to record to learn whether you have gone before the first record of the recordset. You can also use IsBOF along with IsEOF to determine whether the recordset contains any records or is empty. Immediately after you call Open, if the recordset contains no records, IsBOF returns nonzero.When you open a recordset that has at least one record, the first record is the current record and IsBOF returns 0.

If the first record is the current record and you call MovePrev, IsBOF will subsequently return nonzero. If IsBOF returns nonzero and you call MovePrev, an error occurs. If IsBOF returns nonzero, the current record is undefined, and any action that requires a current record will result in an error.

Example

This example uses IsBOF and IsEOF to detect the limits of a recordset as the code scrolls through the recordset in both directions.

// Open a recordset; first record is current
CCustomer rsCustSet(&m_dbCust);
rsCustSet.Open();

if(rsCustSet.IsBOF())
   return;
   // The recordset is empty 

// Scroll to the end of the recordset, past 
// the last record, so no record is current 
while (!rsCustSet.IsEOF())
   rsCustSet.MoveNext();

// Move to the last record
rsCustSet.MoveLast();

// Scroll to beginning of the recordset, before 
// the first record, so no record is current 
while(!rsCustSet.IsBOF())
   rsCustSet.MovePrev();

// First record is current again
rsCustSet.MoveFirst();

Requirements

Header: afxdb.h

See Also

Reference

CRecordset Class

Hierarchy Chart

CRecordset::IsEOF

CRecordset::MoveFirst

CRecordset::MovePrev