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BOF indicates that the current record position is before the first record in a Recordset object.
EOF indicates that the current record position is after the last record in a Recordset object.
The BOF and EOF properties return Boolean values.
Use the BOF and EOF properties to determine whether a Recordset object contains records or whether you've gone beyond the limits of a Recordset object when you move from record to record.
The BOF property returns True (-1) if the current record position is before the first record and False (0) if the current record position is on or after the first record.
The EOF property returns True if the current record position is after the last record and False if the current record position is on or before the last record.
If either the BOF or EOF property is True, there is no current record.
If you open a Recordset object containing no records, the BOF and EOF properties are set to True, and the Recordset object's RecordCount property setting is zero. When you open a Recordset object that contains at least one record, the first record is the current record and the BOF and EOF properties are False.
If you delete the last remaining record in the Recordset object, the BOF and EOF properties may remain False until you attempt to reposition the current record.
This table shows which ADO Recordset Object Move Method methods are allowed with different combinations of the BOF and EOF properties:
Allowing a Move method doesn't guarantee that the method will successfully locate a record; it only means that calling the specified Move method won't generate an error.
The following table shows what happens to the BOF and EOF property settings when you call various Move methods but are unable to successfully locate a record.
BOF
|
EOF
|
|
---|---|---|
MoveFirst, MoveLast
|
Set to True
|
Set to True
|
Move 0
|
No change
|
No change
|
MovePrevious, Move < 0
|
Set to True
|
No change
|
MoveNext, Move > 0
|
No change
|
Set to True
|
This Visual Basic example uses the BOF and EOF properties to display a message if a user tries to move past the first or last record of a recordset. It uses the ADO Recordset Object Bookmark Property to let the user flag a record in a recordset and return to it later.
Public Sub BOFX()
Dim rstPublishers As ADODB.Recordset
Dim strCnn As String
Dim strMessage As String
Dim intCommand As Integer
Dim varBookmark As Variant
` Open recordset with data from Publishers table.
strCnn = "driver={SQL Server};server=srv;" & _
"uid=sa;pwd=;database=pubs"
Set rstPublishers = New ADODB.Recordset
rstPublishers.CursorType = adOpenStatic
` Use client cursor to enable AbsolutePosition property.
rstPublishers.CursorLocation = adUseClient
rstPublishers.Open "SELECT pub_id, pub_name FROM publishers " & _
"ORDER BY pub_name", strCnn, , , adCmdText
rstPublishers.MoveFirst
Do While True
` Display information about current record
` and get user input.
strMessage = "Publisher: " & rstPublishers!pub_name & _
vbCr & "(record " & rstPublishers.AbsolutePosition & _
" of " & rstPublishers.RecordCount & ")" & vbCr & vbCr & _
"Enter command:" & vbCr & _
"[1 - next / 2 - previous /" & vbCr & _
"3 - set bookmark / 4 - go to bookmark]"
intCommand = Val(InputBox(strMessage))
Select Case intCommand
` Move forward or backward, trapping for BOF
` or EOF.
Case 1
rstPublishers.MoveNext
If rstPublishers.EOF Then
MsgBox "Moving past the last record." & _
vbCr & "Try again."
rstPublishers.MoveLast
End If
Case 2
rstPublishers.MovePrevious
If rstPublishers.BOF Then
MsgBox "Moving past the first record." &
_vbCr & "Try again."
rstPublishers.MoveFirst
End If
` Store the bookmark of the current record.
Case 3
varBookmark = rstPublishers.Bookmark
` Go to the record indicated by the stored
` bookmark.
Case 4
If IsEmpty(varBookmark) Then
MsgBox "No Bookmark set!"
Else
rstPublishers.Bookmark = varBookmark
End If
Case Else
Exit Do
End Select
Loop
rstPublishers.Close
End Sub
Copyright © 2003 Sun Microsystems, Inc. All rights reserved.