ID: Q136123
The information in this article applies to:
Moderate: Requires basic macro, coding, and interoperability skills.
This article shows you how you can use a single, bound control for both finding records and for entering data in a form. You can use this technique to find whether the value entered in a field already exists in another record. If the value does exist in another record, the record containing that value is displayed. If the value does not exist in another record, you can continue entering data for the current record.
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.
The Microsoft Access online Help system demonstrates how to use the Combo Box Wizard to find records in your database by selecting a key value from a list. (See "Value List," and then "Finding a Record by Selecting a Value from a List" in the Microsoft Access Help system.) This method is limited in that it is designed to be used with a control not based on any table or query (unbound control). The following example demonstrates how to use a single, bound control to achieve the same functionality.
NOTE: The field to which the control is bound cannot be a required field, and it cannot have a validation rule that allows Null values. Make sure that the field's Required property is set to No and that its ValidationRule property does not allow Null values.
To use a single bound control for both finding records and for entering data in a form, follow these steps:
1. Open the sample database Northwind.mdb.
2. Create a new module with the following declarations and functions:
' *******************************************************
' DECLARATIONS SECTION
' *******************************************************
Option Explicit
Dim Found
Function Find_BeforeUpdate (F As Form)
Dim RS As Recordset, C As Control
Set C = Screen.ActiveControl
Set RS = F.RecordsetClone
On Error Goto Err_Find_BeforeUpdate
' Try to find a record with a matching value.
Select Case RS.Fields(C.ControlSource).Type
' Find using Numeric data type key value?
Case DB_INTEGER, DB_LONG, DB_CURRENCY, DB_SINGLE, _
DB_DOUBLE, DB_BYTE
RS.FindFirst "[" & C.ControlSource & "]=" & C
' Find using Date data type key value?
Case DB_DATE
RS.FindFirst "[" & C.ControlSource & "]=#" & C & "#"
' Find using Text data type key value?
Case DB_TEXT
RS.FindFirst "[" & C.ControlSource & "] = """ & C & """"
Case Else
MsgBox "ERROR: Invalid data type for '" & C.Name & "'!"
DoCmd.CancelEvent
Exit Function
End Select
' If a record is found, save the found record's bookmark.
If RS.NoMatch Then
Found = Null
Else
Found = RS.Bookmark
End If
' If the record is found...
' ...cancel the BeforeUpdate event
' ...undo changes made to the current record
' ...and TAB to the next control to trigger the OnExit routine.
If Not IsNull(Found) Then
DoCmd.CancelEvent
SendKeys "{ESC 2}{TAB}", False
End If
Exit Function
Err_Find_BeforeUpdate:
MsgBox "ERROR: Err " & Err & ": " & Error$, 48
DoCmd.CancelEvent
Exit Function
End Function
Function Find_OnExit ()
' If the record is found, cancel the OnExit routine to stay
' in the control and go find the record.
If Not IsNull(Found) And Len(Found) <> 0 Then
DoCmd.CancelEvent
' Synchronize the form record with the found record.
Screen.ActiveForm.Bookmark = Found
Found = Null
End If
End Function
Customer ID control as follows:
BeforeUpdate: =Find_BeforeUpdate(Form)
OnExit: =Find_OnExit()
"AROUT" (without the quotation marks), and then press ENTER. Note that
Microsoft Access finds and displays the Around The Horn customer.
and then press ENTER. Because this key value does not exist, you can
continue entering data for the record.
The Find_BeforeUpdate() function uses the FindFirst method to search the recordset that the form is based on to see if the value entered in the control exists in the table.
If the value does not exist, the global variable Found is set to NULL and the function exits. If the value does exist, the global variable Found is set to the bookmark of the found record to be used by the Find_OnExit() function.
Before the found record can be presented, the BeforeUpdate event must be canceled, and a SendKeys action must send two ESC keys to undo changes to the current record.
Next, the SendKeys action sends a TAB key to exit the field. This event triggers the Find_OnExit() function, which checks to see if the find was successful. If it was, the CancelEvent action is run to prevent exiting the control, and then the form record is synchronized with the found record by setting its bookmark equal to the bookmark of the found record. Found is then reset back to NULL.
For more information about this topic in Microsoft Access version 2.0, please see the following article in the Microsoft Knowledge Base:
ARTICLE-ID: Q115189
TITLE : ACC2: How to Find a Record Using a Bound Control
Keywords : kbusage FmsEvnt FmsHowto
Version : 7.0 97
Platform : WINDOWS
Hardware : x86
Issue type : kbhowtoLast Reviewed: November 21, 1998