Microsoft KB Archive/210239

= ACC2000: How to Use a Bound Control to Find a Record =

Article ID: 210239

Article Last Modified on 10/11/2006

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APPLIES TO


 * Microsoft Access 2000 Standard Edition

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This article was previously published under Q210239



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

This article applies only to a Microsoft Access database (.mdb).



SUMMARY
This article shows you how you can use a single, bound control for both finding records and for typing data in a form. You can use this technique to find whether the value typed 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 typing data for the current record.



MORE INFORMATION
Microsoft Access online Help demonstrates how to use the Combo Box Wizard to find records in your database by selecting a key value from a list. However, 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 both for finding records and for typing data in a form, follow these steps:  Start Microsoft Access and open the sample database Northwind.mdb.  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

 Open the Customers form in Design view, and then set the properties for the Customer ID control as follows:

BeforeUpdate: =Find_BeforeUpdate(Form)

OnExit: =Find_OnExit

 View the Customers form in Form view. Click the New Record button at the bottom of the form. In the CustomerID control, type AROUT, and then press ENTER.

Note that Microsoft Access finds and displays the Around The Horn customer. Again, click the New Record button at the bottom of the form. In the Customer ID control, type POPSI, and then press ENTER. Because this key value does not exist, you can continue typing data for the record.

How the Sample Functions Work
The Find_BeforeUpdate function uses the FindFirst method to search the recordset that the form is based on to determine whether the value typed 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.

Keywords: kbhowto kbusage KB210239

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