multiple selection

[kevcar40]

Hi
i have a form that allows the user to select criteria for searching on
what i am trying to create now is a search for shifts

i have three check boxes on the form
ashift
bshift
cshift

i want the user to be able to select any one(only one) and return the
relevent data (done this part)

i also want the user to be able to select two shifts (but never three)
ie
ashift ashift
bshift
bshift or bshift or
cshift
and again return the relevent data

can anyone please help me with this second part

thanks

kevin

[Steve]

Re: multiple selection

What you would do is put some code in the AfterUpdate event of each
checkbox control to see if two other checkboxes are selected.

Example:

'Method: CheckChecks()
'Purpose: Determines how many checkboxes are checked
'Returns: Integer representing the number of checked checkboxes
Public Function CheckChecks() As Integer
'numChecked holds the number of checked boxes
Dim numChecked as Integer
If Me.AShift.Value =True Then
'AShift is selected
numChecked=numC hecked+1
End If
If Me.BShift.Value =True Then
'BShift is selected
numChecked=numC hecked+1
End If
If Me.CShift.Value =True Then
'CShift is selected
numChecked=numC hecked+1
End If

'Return the number of checked boxes
CheckChecks=num Checked
End Function

In the AfterUpdate event of each checkbox, put in code like this:

If CheckChecks>2 Then
'Tell user to select only two boxes
MsgBox "You can only check two boxes at a time", "Alert"
'At this point, un-check the box the user has just selected
Me.[AShift][BShift][CShift].Value=False
End If

When your user tries to check 3 boxes, he will get a message telling
him to check only two of them. The box he just selected will be
un-checked.

*************** *************** *************** *
Another way to do this is to disable the third checkbox when the user
has already selected two of them. You could do this by putting code in
the AfterUpdate event of each box like so:

'In AShift's AfterUpdate
If Me.BShift.Value =True Then
Me.CShift.Enabl ed=False
ElseIf Me.CShift.Value =True Then
Me.BShift.Enabl ed=False
End If

'In BShift's AfterUpdate
If Me.AShift.Value =True Then
Me.CShift.Enabl ed=False
ElseIf Me.CShift.Value =True Then
Me.AShift.Enabl ed=False
End If


The problem with this method is that it would be kind of half-cartesian
(you would have to check for two-thirds of the possible permutations of
those checkboxes). This means that your code in each checkbox's
AfterUpdate will grow exponentially as soon as you start adding
checkboxes to that structure (i.e. if you decide you want to add a
fourth shift).

[Thelma Lubkin]

Re: multiple selection

Steve <theonesteve@gm ail.com> wrote:
: What you would do is put some code in the AfterUpdate event of each
: checkbox control to see if two other checkboxes are selected.

: *************** *************** *************** *
: Another way to do this is to disable the third checkbox when the user
: has already selected two of them. You could do this by putting code in
: the AfterUpdate event of each box like so:

: 'In AShift's AfterUpdate
: If Me.BShift.Value =True Then
: Me.CShift.Enabl ed=False
: ElseIf Me.CShift.Value =True Then
: Me.BShift.Enabl ed=False
: End If

: 'In BShift's AfterUpdate
: If Me.AShift.Value =True Then
: Me.CShift.Enabl ed=False
: ElseIf Me.CShift.Value =True Then
: Me.AShift.Enabl ed=False
: End If


: The problem with this method is that it would be kind of half-cartesian
: (you would have to check for two-thirds of the possible permutations of
: those checkboxes). This means that your code in each checkbox's
: AfterUpdate will grow exponentially as soon as you start adding
: checkboxes to that structure (i.e. if you decide you want to add a
: fourth shift).

Another problem with this approach is that it takes away user's
ability to change his/her mind. If CShift has become disabled,
user can't decide to uncheck AShift and take CShift instead
before asking for action...unless you write yet more code.
--thelma

[kevcar40]

Re: multiple selection

Thanks all