Record locking in vba - vba

Question

i have a VBA application which is spitted into two one for front end; and backend while updating how to prevent two users edit it ??

Answer 1

Access has locking. From Access Help:
Specify the locking level used in an Access database in a multiuser environment
On the Tools menu, click Options.
Click the Advanced tab.
To make record-level locking the new
default setting for the current
Microsoft Access database, select the
Open databases using record-level
locking check box.
To make page-level
locking the new default setting for
the current Access database, clear the
Open databases using record level
locking check box.
Notes
This setting takes place the next time
you open the Access database, but you
must use the Open command on the File
menu rather than the list of most
recently used files at the end of the
File menu. This behavior is the same
as the setting for the default open
mode.
If you select Open databases using
record level locking, this becomes the
default behavior for access to data
through a form, a datasheet, and code
that uses a recordset object to loop
through records, but not through
action queries, nor through code that
performs bulk operations using SQL
statements. For more information, see
Chapter 16, "Multiuser Database
Applications," in the Microsoft Office
2000/Visual Basic Programmer's Guide.

Answer 2

Yoy may try to invoke pessimistic locking
Dim cnn As ADODB.Connection
Dim rst As ADODB.Recordset
Set cnn = New ADODB.Connection
cnn.ConnectionString = " Provider=sqloledb;" & _
"Data Source=(local);Initial Catalog=pubs;uid=sa;pwd="
cnn.Open
Set rst = New ADODB.Recordset
rst.ActiveConnection = cnn
rst.CursorType = adOpenKeyset
rst.LockType = adLockPessimistic 'Invoke Pessimistic Locking
rst.CursorLocation = adUseServer
rst.Open "Select * from Table Where ID ='" _
& strID & "'", _
Options:=adCmdText
rst!Name = "New name" 'Lock occurs here
'... when it is locked, you may do other operations
rst.Update 'Lock Released Here
You will have to implement error handling, because when 2nd client wants to edit and cannot lock the record during timeout, error will be raised.
However pessimistic locking is not the best scenario, I would think about optimistic locking and either First Wins or Last Wins strategy
Here is an online book Alison Balter's mastering Microsoft Access 2000 development, it should help you.