Hope this was what you were expecting! Here is some code from my project
that using a "timestamp" (aka rowversion)
"A future release of Microsoft® SQL ServerT may modify the behavior of the
Transact-SQL timestamp data type to align it with the behavior defined in
the standard. At that time, the current timestamp data type will be replaced
with a rowversion data type.
Microsoft® SQL ServerT 2000 introduces a rowversion synonym for the
timestamp data type. Use rowversion instead of timestamp wherever possible
in DDL statements. rowversion is subject to the behaviors of data type
synonyms."
(As far as what to do with it, that depends. I shove mine into ViewState
when the page load, and then read it again after postback)
Example of typical sproc:
CREATE PROCEDURE usp_SomeSPROC(
@MyID int,
@RowVersion rowversion OUTPUT,
<blah blah>
)
AS
SET NOCOUNT ON
BEGIN TRAN
DECLARE @ErrorSave int
DECLARE @CurrRowVersion rowversion
SELECT @CurrRowVersion = [RowVersion] FROM MyTable WHERE MyID = @MyID
IF @CurrRowVersion <> @RowVersion
BEGIN
ROLLBACK
RETURN -1
END
<do some tsql statements here>
IF @@ERROR <> 0
SET @ErrorSave = @@ERROR
SELECT @RowVersion = [RowVersion] FROM MyTable WHERE MyID = @MyID
IF @ErrorSave <> 0
ROLLBACK
ELSE
COMMIT
Back in my code, typical SQL method:
This is all psuedo code...
Public RowVersion(8) As Byte
Public Sub MyMethod(<blah blah>)
Dim cn As SqlConnection = New
SqlConnection(ConfigurationSettings.AppSettings("C onnectionString"))
Dim cmd As SqlCommand = New SqlCommand("usp_SomeSPROC", cn)
cmd.CommandType = CommandType.StoredProcedure
cmd.Parameters.Add("@MyID", Me.MyID)
cmd.Parameters.Add("RETURN_VALUE", SqlDbType.Int).Direction =
ParameterDirection.ReturnValue
With cmd.Parameters.Add("@RowVersion", SqlDbType.Timestamp)
.Value = Me.RowVersion
.Direction = ParameterDirection.InputOutput
End With
Try
cn.Open()
cmd.ExecuteNonQuery()
If CInt(cmd.Parameters("RETURN_VALUE").Value) = -1 Then
' this row has been modified by somebody else!!!
Throw New ModifiedByAnotherException
End If
Me.RowVersion = CType(cmd.Parameters("@RowVersion").Value,
Byte())
Catch ex As SqlException
Throw New Exception("error while doing mymethod!", ex)
Finally
cn.Close()
End Try
End Sub
Public Class ModifiedByAnotherException
Inherits System.ApplicationException
Public Sub New()
MyBase.New("Timesheet was modified by another user!")
End Sub
Public Sub New(ByVal InnerException As Exception)
MyBase.New("Timesheet was modified by another user!",
InnerException)
End Sub
End Class
HTH,
Greg
"Roger Twomey" <ro******@vnet.on.ca> wrote in message
news:%2****************@TK2MSFTNGP14.phx.gbl...
I have a database that I don't want to lock. I decided that before any
updates can occur I would check a timestamp value and ensure that nobody
else updated before I did (avoiding the 'last update wins' scenario).
I have a problem, I can read the Timestamp from the db when I read the
record. I currently use the data to pre-fill a form (gee go figure ;) )
and
the user changes some values and updates.
I don't know what to DO with the timestamp value while I am holding it. I
have tried putting it into a hidden value on the form but the value does
not
seem to translate back and forth.
Do I have to store it as in memory as part of the session or can I somehow
convert to and from text??
I have about 0 experience working with byte arrays so the best answer is
one
with an example.
Thanks.
