How do I access the selected rows in Access?

I have a form开发者_运维知识库 which includes a data sheet. I would like to make it possible for a user to select multiple rows, click on a button and have some sql query run and perform some work on those rows.

Looking through my VBA code, I see how I can access the last selected record using the CurrentRecord property. Yet I don't see how I can know which rows were selected in a multiple selection. (I hope I'm clear...)

What's the standard way of doing this? Access VBA documentation is somewhat obscure on the net...

Thanks!

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I used the technique similar to JohnFx

To trap the Selection height before it disappears I used the Exit event of the subform control in the Main form.

So in the Main form:

Private Sub MySubForm_Exit(Cancel As Integer)

  With MySubForm.Form
    m_SelNumRecs = .SelHeight
    m_SelTopRec = .SelTop
    m_CurrentRec = .CurrentRecord
  End With

End Sub

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Here is the code to do it, but there is a catch.

Private Sub Command1_Click()
     Dim i As Long
     Dim RS As Recordset
     Dim F As Form

     Set F = Me.sf.Form
     Set RS = F.RecordsetClone

     If F.SelHeight = 0 Then Exit Sub

     ' Move to the first selected record.
     RS.Move F.SelTop - 1

     For i = 1 To F.SelHeight
       MsgBox RS![myfield]
       RS.MoveNext
     Next i

End Sub

Here's the catch: If the code is added to a button, as soon as the user clicks that button, the selection is lost in the grid (selheight will be zero). So you need to capture that info and save it to a module level variable either with a timer or other events on the form.

Here is an article describing how to work around the catch in some detail.
http://www.mvps.org/access/forms/frm0033.htm

Catch 2: This only works with contiguous selections. They can't select mutliple non-sequential rows in the grid.

Update:
There might be a better event to trap this, but here is a working implementation using the form.timerinterval property that i have tested (at least in Access 2k3, but 2k7 should work just fine)

This code goes in the SUBFORM, use the property to get the selheight value in the master form.

Public m_save_selheight As Integer

Public Property Get save_selheight() As Integer
    save_selheight = m_save_selheight
End Property

Private Sub Form_Open(Cancel As Integer)
    Me.TimerInterval = 500
End Sub

Private Sub Form_Timer()
    m_save_selheight = Me.selheight
End Sub

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I've tried doing something like that before, but I never had any success with using a method that required the user to select multiple rows in the same style as a Windows File Dialog box (pressing Ctrl, Shift, etc.).

One method I've used is to use two list boxes. The user can double click on an item in the left list box or click a button when an item is selected, and it will move to the right list box.

Another option is to use a local table that is populated with your source data plus boolean values represented as checkboxes in a subform. After the user selects which data they want by clicking on checkboxes, the user presses a button (or some other event), at which time you go directly to the underlying table of data and query only those rows that were checked. I think this option is the best, though it requires a little bit of code to work properly.

Even in Access, I find sometimes it's easier to work with the tables and queries directly rather than trying to use the built-in tools in Access forms. Sometimes the built-in tools don't do exactly what you want.

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A workaround to the selection loss when the sub form loses the focus is to save the selection in the Exit event (as already mentioned by others).

A nice addition is to restore it immediately, using timer, so that the user is still able to see the selection he made.

Note: If you want to use the selection in a button handler, the selection may not be restored already when it executes. Make sure to use the saved values from the variables or add a DoEvents at the beginning of the button handler to let the timer handler execute first.

Dim m_iOperSelLeft As Integer
Dim m_iSelTop As Integer
Dim m_iSelWidth As Integer
Dim m_iSelHeight As Integer

Private Sub MySubForm_Exit(Cancel As Integer)

    m_iSelLeft = MySubForm.Form.SelLeft
    m_iSelTop = MySubForm.Form.SelTop
    m_iSelWidth = MySubForm.Form.SelWidth
    m_iSelHeight = MySubForm.Form.SelHeight

    TimerInterval = 1

End Sub

Private Sub Form_Timer()

    TimerInterval = 0

    MySubForm.Form.SelLeft = m_iSelLeft - 1
    MySubForm.Form.SelTop = m_iSelTop
    MySubForm.Form.SelWidth = m_iSelWidth
    MySubForm.Form.SelHeight = m_iSelHeight

End Sub

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There is another solution.

The code below will show the number of selected rows as soon as you release the mouse button. Saving this value will do the trick.

Private Sub Form_MouseUp(Button As Integer, Shift As Integer, X As Single, Y As Single)

        MsgBox Me.SelHeight

End Sub

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Use a Global variable in the form, then refer to that in the button code.

Dim g_numSelectedRecords as long

Private Sub Form_MouseUp(Button As Integer, Shift As Integer, X As Single, Y As Single)
   g_numSelectedRecords = Me.SelHeight
End Sub


Dim formRecords As DAO.Recordset
Dim i As Long

Set formRecords = Me.RecordsetClone

' Move to the first record in the recordset.
formRecords.MoveFirst

' Move to the first selected record.
formRecords.Move Me.SelTop - 1

For i = 1 To numSelectedRecords
    formRecords.Edit
    formRecords.Fields("Archived") = True
    formRecords.Update
    formRecords.MoveNext
Next i

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Why not use an array or recordset and then every time the user clicks on a row (either contiguous or not, save that row or some identifier into the recordset. Then when they click the button on the parent form, simply iterate the recordset that was saved to do what you want. Just don't forget to clear the array or recordset after the button is clicked.?

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Another workaround to keeping the selection while attempting to execute a procedure - Instead of leaving the datasheet to activate a button, just use the OnKeyDown event and define a specific keycode and shift combination to execute your code.

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The code provided by JohnFx works well. I implemented it without a timer this way (MS-Access 2003):
1- Set the Form's Key Preview to Yes
2- put the code in a function
3- set the event OnKeyUp and OnMouseUp to call the function.

Option Compare Database
Option Explicit

Dim rowSelected() As String

Private Sub Form_Load()
'initialize array
ReDim rowSelected(0, 2)
End Sub

Private Sub Form_Current()
' if cursor place on a different record after a selection was made 
' the selection is no longer valid
If "" <> rowSelected(0, 2) Then
  If Me.Recordset.AbsolutePosition <> rowSelected(0, 2) Then
    rowSelected(0, 0) = ""
    rowSelected(0, 1) = ""
    rowSelected(0, 2) = ""
  End If
End If
End Sub

Private Sub Form_KeyUp(KeyCode As Integer, Shift As Integer)
rowsSelected
If KeyCode = vbKeyDelete And Me.SelHeight > 0 Then
    removeRows
End If
End Sub

Private Sub Form_MouseUp(Button As Integer, Shift As Integer, X As Single, Y As Single)
rowsSelected
End Sub

Sub rowsSelected()
Dim i As Long, rs As DAO.Recordset, selH As Long, selT As Long
selH = Me.SelHeight
selT = Me.SelTop - 1
If selH = 0 Then
    ReDim rowSelected(0, 2)
    Exit Sub
Else
    ReDim rowSelected(selH, 2)
    rowSelected(0, 0) = selT
    rowSelected(0, 1) = selH
    rowSelected(0, 2) = Me.Recordset.AbsolutePosition ' for repositioning 
    Set rs = Me.RecordsetClone
    rs.MoveFirst ' other key touched caused the pointer to shift
    rs.Move selT
    For i = 1 To selH
        rowSelected(i, 0) = rs!PositionNumber
        rowSelected(i, 1) = Nz(rs!CurrentMbr)
        rowSelected(i, 2) = Nz(rs!FutureMbr)
        rs.MoveNext
    Next
    Set rs = Nothing
    Debug.Print selH & " rows selected starting at " & selT 
End If
End Sub

Sub removeRows()
' remove rows in underlying table using collected criteria in rowSelected()
    Me.Requery
' reposition cursor
End Sub

Private Sub cmdRemRows_Click()
If Val(rowSelected(0, 1)) > 0 Then
    removeRows
Else
    MsgBox "To remove row(s) select one or more sequential records using the record selector on the left side."
End If
End Sub