form checkboxes correspond to table entry

[gixxer5]

Okay here goes,

I have 3 tables

[Person Table]
Person_ID: text;
first_name: text;
last_name: text;

[Group_Definition Table]
Group_ID; Autonumber;
Group_Desc: Text;

[Person_Group_Membership]
person_id: text;
Group_ID; number;

Sample Data

[Person Table]
aaaa Jim Johnson
bbbb Joe Jones
cccc John Doe

[Group_Definition Table]
1 GroupA
2 GroupB
3 GroupC

[Person_Group_Membership]
aaaa 1
bbbb 1
aaaa 2
cccc 3

Now, I would like to have a form, where it lists the persons name, and a group of check boxes, one checkbox for each group. as you scroll through the people, there is a check in the box if the person has an entry in that group; also, if a check is placed in the box, a corresponding entry is made in the person_Group_membership table.

I am just not sure of the proper way to go about doing this. Thanks!

[NeoPa]

Nicely worded question :)
Unfortunately I think this is a CrossTab query question (not an area I'm very good in).
I think though, that a crosstab query of the groups per user would be required. It would not be updateable though, so would require code in the AfterUpdate events of the CheckBoxes to add and delete records as and when checked. Such code would always need to be succeeded with a call of Me.Requery. Does this make sense?

PS. You may get some other, better ideas from the other Experts.

[FishVal]

Hi, gixxer.

It will require some unusual design of the form.

• the simplest way to represent person's membership is to use subform (datasheet or continuous forms view), lets say main form based on [Person Table] is [frmPeople], subform is [frmMembership]
  • as soon as you want to see all groups with checkboxes indicating membership the recordsource for form object of this subform should be outer join of [Group_Definition Table] and [Person_Group_Membership], like the following
    

    SELECT [Group_Definition Table].Group_Desc, IIf(IsNull(t.Person_ID),False,True) AS blnBelongsTo, [Group_Definition Table].Group_ID
    FROM [Group_Definition Table] LEFT JOIN (SELECT [Person_Group_Membership].* FROM [Person_Group_Membership] WHERE [Person_Group_Membership].Person_ID=Forms!frmPeople!Person_ID) AS t ON [Group_Definition Table].Group_ID = t.Group_ID;
     

    note: controlsource for future checkbox is calculated field [blnBelongsTo], [Person_Group_Membership] is filtered by Forms!frmPeople!Person_ID prior to join because native Access form/subform link via master/child fields will not work
  • you need to bind the query fields to [frmMembership] controls ([Group_ID] control should be invisible)
  • [frmMembership] properties: allow additions/deletions/edit/filters should be set to "no"
• the action check/uncheck person's membership in group actually means append/delete record to/from [Person_Group_Membership]
• you may handle [blnBelongsTo] checkbox MouseDown event to run appropriate append/delete queries. Something like this:
  

  Private Sub blnBelongsTo_MouseDown(Button As Integer, Shift As Integer, X As Single, Y As Single)
   
      'Exit sub if parent form on *New record* or other than Leftbutton was pressed
      If IsNull(Me.Parent!keyPersonID) Or Button <> 1 Then Exit Sub
   
      With DoCmd
          .SetWarnings False
          Select Case Me.blnBelongsTo
              Case True
                  .RunSQL "DELETE * FROM [Person_Group_Membership] WHERE Person_ID='" _
                      & Me.Parent!keyPerson_ID & "' AND Group_ID=" & _
                      Me.Group_ID & ";"
              Case False
                  .RunSQL "INSERT INTO  [Person_Group_Membership] (Person_ID, Group_ID)" & _
                      " VALUES ('" & Me.Parent!Person_ID & ", " & _
                      Me.Group_ID & ");"
          End Select
          .SetWarnings True
          Me.Requery
      End With
   
  End Sub
   

[MarkKubicki]

Any chance the response could be re-posted?

Some of the text in the first code example has been truncated to be nothing more than the letter "T" making it a bit difficult to follow...

big thanks if you can,
mark

[Rabbit]

Which post are you referring to? I don't see anything cut off. Did you scroll to the right in the code box?

[MarkKubicki]

in the first block of code:

SELECT [Group_Definition Table].Group_Desc, IIf(IsNull(t.Person_ID),False,True) AS blnBelongsTo, [Group_Definition Table].Group_ID
FROM [Group_Definition Table] LEFT JOIN (SELECT [Person_Group_Membership].* FROM [Person_Group_Membership] WHERE [Person_Group_Membership].Person_ID=Forms!frmPeople!Person_ID) AS t ON [Group_Definition Table].Group_ID = t.Group_ID;

you'll note that a few time there is a letter "t", which refers to something...

[Rabbit]

You mean the "t." ? That's not cut off. It's referring to an alias given to the table.

[NeoPa]

As Rabbit says that is an ALIAS defined in the SQL. It may help to see it all laid out in a more readable format :

SELECT [Group_Definition Table].Group_Desc
     , IIf(IsNull(t.Person_ID),False,True) AS blnBelongsTo
     , [Group_Definition Table].Group_ID
FROM   [Group_Definition Table]
       LEFT JOIN
       (SELECT [Person_Group_Membership].*
        FROM   [Person_Group_Membership]
        WHERE  [Person_Group_Membership].Person_ID=Forms!frmPeople!Person_ID) AS t
  ON   [Group_Definition Table].Group_ID = t.Group_ID;

Always bear in mind, if you can't read it well on the page then you can always copy and paste it into something more controllable (EG. Notepad.) and read it there ;-)

[MarkKubicki]

I sincerly appreciate your reply, and at the same time apologize...
"alias" is something that as a self-taught blah, blah..., I'm aware of, but haven't yet given myself much experience with.

never-the-less,
I'm combing thru the code and the text of the page, and I can't seem to locate where the alias has been assigned.
I would think that it is in the first line of code:

SELECT [Group_Definition Table].Group_Desc, 
IIf(IsNull(t.Person_ID),False,True) AS blnBelongsTo, [Group_Definition Table].Group_ID 
 

where t would then refer to the [Group_Definition Table], but the code then goes on to reference the field (t.Person_ID) which is not part of that table.

For the moment (rather then getting side tracked in learning about "alias"), would you tell me which table 't' refers to (I presume either: [Person Table] or [Person_Group_Membership] )

With thanks in advance,
Mark

[Rabbit]

NeoPa's reformatted code block, line number 8, at the very end

[MarkKubicki]

AH.
BIG THANKS!
m.

[NeoPa]

For anyone else struggling with that, the subquery (in parentheses - See Subqueries in SQL) is ALIASed in order to refer to it directly.

ALIAS simply means to assign a new name to a construct. This can be for tables, fields, queries, subqueries defined within parentheses, etc.

In SQL this is done using the ALIAS keyword, which can be abbrviated to AS as well as left out completely. Here are some illustrative examples :

SELECT [tblEmployee].[Employee ID] ALIAS [EmpID]
     , [tblEmployee].[Employee Name] AS [EmpName]
FROM   [Employee Table] [tblEmployee]

This illustrates each possibility. I've underlined the ALIAS in each case.