ACC: How to Move List Box Items to Another List Box (7.0/97)

ID: Q177117


The information in this article applies to:
  • Microsoft Access versions 7.0, 97


SUMMARY

Moderate: Requires basic macro, coding, and interoperability skills.

This article shows you how to create a form that has two list boxes that imitate the multiple-selection capability reflected in Microsoft Access Wizards.

This article assumes that you are familiar with Visual Basic for Applications and with creating Microsoft Access applications using the programming tools provided with Microsoft Access. For more information about Visual Basic for Applications, please refer to your version of the "Building Applications with Microsoft Access" manual.

NOTE: The method provided in this article is suitable for single-user environments only. If this method is used in a multiuser environment, what one user does may interfere with the actions of another user.


MORE INFORMATION

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http://www.microsoft.com/mcsp/
For more information about the support options available from Microsoft, please see the following page on the World Wide Web:

http://www.microsoft.com/support/supportnet/overview/overview.asp

The method described in this article uses a Yes/No field in the table to indicate which records are selected. One list box displays the Yes records and the other displays the No records. To move items from one list box to the other, the Yes/No field of the selected record is set to the appropriate state and the list boxes are then requeried to update their respective lists.

In addition to the two list boxes, the form also has three command buttons. By using the command buttons, you can add items to, or delete items from the list box. You can also double-click an item in a list box to move it to the other list box.

To create the list boxes with the multiple-selection capability, you need to do the following:

   A. Create a table that contains the data for the list boxes. 

   B. Create two queries based on the table created in step A. 

   C. Create the form that will contain the list boxes, code modules, and
      command buttons. 

A. Create a table that contains the data for the list boxes

  1. Open the sample database Northwind.mdb and create the following new table:


  2. 
             Table: Table1
             ---------------------------------------------------
             Field Name: List
                Data Type: Text
                Caption: Items that will be provided in list
    
             Field Name: Selected
                Data Type: Text
                Caption: Indicates if the item has been selected
    
             Table Properties: Table1
             ------------------------
             PrimaryKey: List 
  3. View the Table1 table in Datasheet view. Add five records to the table. For each record, type the following sample data:


  4. 
             List         Selected
             ----         --------
             one           Yes
             two           Yes
             three         Yes
             four          Yes
             five          Yes 

B. Create two queries based on the table created in step A

  1. Create the following new query based on the Table1 table and save it as Select Yes:


  2. 
             Query: Select Yes
             -------------------------------
             Field: List
                Show: Yes
                Criteria: [selected] = "YES" 
  3. Create another new query based on the Table1 table as follows and save it as Select No:


  4. 
          Query: Select No
          ------------------------------
           Field: List
             Show: Yes
             Criteria: [selected] = "NO" 

C. Create a form containing list boxes, code, and command buttons

  1. Create a new blank form and save it as SelectList.


  2. With the SelectList form open in Design view, on the View menu, click Code, and then type the following line in the Form module Declarations section if it is not already there:


  3. 
    Option Explicit 
  4. Type the following three functions in the Form module:


  5. 
           '=======================================================
           ' The following function opens the table and changes the
           ' selected value from YES to NO, and then runs the
           ' query for the two list boxes so that they will display
           ' the updated values.
           '=======================================================
           Function Add()
              Dim MyDB As Database
              Dim MyTable As Recordset
              Dim y As Control
    
              Set y = Me![list0]
    
              If IsNull(y) Then
                 MsgBox "Please select something in the list."
              Else
                 Set MyDB = DBEngine.Workspaces(0).Databases(0)
                 Set MyTable = MyDB.OpenRecordset("Table1")
    
                 MyTable.Index = "PrimaryKey"
                 MyTable.Seek "=", y
    
                 With MyTable
                    .Edit
                    !Selected = "no"
                    .Update
                 End With
    
                 Set MyTable = Nothing
                 Me![list0].Requery
                 Me![list2].Requery
              End If
           End Function
    
           '=======================================================
           ' The following function opens the table and changes the
           ' selected value from NO to YES, and then runs the
           ' query for the two list boxes so that they will display
           ' the updated values.
           '=======================================================
    
           Function Del()
              Dim MyDB As Database
              Dim MyTable As Recordset
              Dim y As Control
    
              Set y = Me![list2]
    
              If IsNull(y) Then
                 MsgBox "Please select something in the list."
              Else
                 Set MyDB = DBEngine.Workspaces(0).Databases(0)
                 Set MyTable = MyDB.OpenRecordset("Table1")
    
                 MyTable.Index = "PrimaryKey"
                 MyTable.Seek "=", y
    
                 With MyTable
                    .Edit
                    !Selected = "yes"
                    .Update
                End With
    
                 Set MyTable = Nothing
                 Me![list0].Requery
                 Me![list2].Requery
              End If
           End Function
    
           '=======================================================
           ' The following function sets all values in the Selected
           ' field to YES, and then runs the query for the two list
           ' boxes so that they will display the updated values.
           '=======================================================
           Function Clear()
              Dim MyDB As Database
              Dim MyTable As Recordset
    
              Set MyDB = DBEngine.Workspaces(0).Databases(0)
              Set MyTable = MyDB.OpenRecordset("Table1")
    
              On Error GoTo erhandle
              With MyTable
                .MoveFirst
                Do Until .EOF
                    .Edit
                    !Selected = "yes"
                    .Update
                    .MoveNext
                Loop
    
              End With
              Set MyTable = Nothing
              Me![list0].Requery
              Me![list2].Requery
    
           erhandle:
                 Resume Next
    
           End Function 
  6. Save and close the Form module.


  7. Add the following list box and command button controls to the SelectList form:


  8. 
             List Box:
             -----------------------------
             Name: List0
                RowSourceType: Table/Query
                RowSource: Select Yes
                OnDblClick: =Add()
    
             List Box:
             -----------------------------
             Name: List2
                RowSourceType: Table/Query
                RowSource: Select No
                OnDblClick: =Del()
    
             Command Button:
             --------------------
             Name: Button One
                Caption: Clear
                OnClick: =Clear()
    
             Command Button:
             --------------------
             Name: Button Two
                Caption: Add Item
                OnClick: =Add()
    
             Command Button:
             -----------------------
             Name: Button Three
                Caption: Delete Item
                OnClick: =Del() 
  9. View the SelectList form in Form view.

    Note that the first list box, List0, displays all the items in the Table1 table you can select. You can use the Clear, Add Item, or Delete Item buttons to add or remove items from the second list box, List2. You can also double-click an item in a list box to move it to the other list box.



REFERENCES

For more information about list boxes, search the Help Index for "List Boxes," or ask the Microsoft Access 97 Office Assistant.

Additional query words: combo fill inf multipleselection multiple-select multipleselect

Keywords : FmsCmbo
Version : WINDOWS:7.0,97
Platform : WINDOWS
Issue type : kbhowto


Last Reviewed: July 6, 1999
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