Generating PK for MTS objects

[tchbansi]

Im building an application with MTS and SQLServer.
Im facing the problem of generating unique ID (primary key) to my objects.
I was thinking of creating a class for generating the PK. but I dont see how to do it in VB+MTS.
anyone has any ideas?

 

[zallen]

Why do you generate unique ID (primary key) to objects.
Any example???

 

[tchbansi]

Example: Order and OrderDetails.
You have 2 classes: cOrder and cOrderDetail that are persist in the table t_Order and t_OrderDetail(id,, with t_OrderDetail having a foreign key pointing to t_Order.

When you want to save a new order+its details, you need to generate a unique id for cOrder to be able to save the cOrderDetails objects (for the foreign key).

 

[zallen]

In Delphi,it is easy to handle:

in middle tier:
.build master-detail relation between tblOrder and tblOrderDetail
.package the data to client through TDataSetProvider

in client tier:
.recreate the master-detail relation by TClientDataSet

 

[dfw]

'Here is a Class I use for Generating Guids
'Just Reference It and ask for GenerateGUID
Option Explicit
'Class Generates GUIDS
'DFW 07/25/00
Private Type Guid
Data1 As Long
Data2 As Long
Data3 As Long
Data4(8) As Byte
End Type
Private Declare Function CoCreateGuid _
Lib "ole32.dll" (pguid As Guid) As Long
Private Declare Function StringFromGUID2 Lib "ole32.dll" _
(rguid As Any, ByVal lpstrClsId As Long, _
ByVal cbMax As Long) As Long
'Gets the Computer name
Private Declare Function GetComputerName& Lib "kernel32" Alias "GetComputerNameA" (ByVal Buffer As String, nSize As Long)

Public Function GenerateGUID() As String
'***************************************************
'Purpose: Function to Generate GUID
'Author: David F. Wade
'Date: 07/25/00

Dim uGUID As Guid
Dim sGUID As String
Dim bGUID() As Byte
Dim lLen As Long
Dim RetVal As Long
lLen = 40
bGUID = String(lLen, 0)
CoCreateGuid uGUID
'Convert the structure into a displayable string
RetVal = StringFromGUID2(uGUID, VarPtr(bGUID(0)), lLen)
sGUID = bGUID
If (Asc(Mid$(sGUID, RetVal, 1)) = 0) Then RetVal = RetVal - 1
GenerateGUID = Left$(sGUID, RetVal)
End Function
Public Function GetGuid() As String
Dim strGUID As String
strGUID = GenerateGUID
strGUID = Mid(strGUID, 2, 36)
GetGuid = Replace(strGUID, "-", "&quot

End Function

 

[Liberty]

Have you considered using a hierachical recordset. It takes care of your problem more efficiently. You can get the recordset from the server as a connectionless recordset; update the records on the fly and when done you can send the recordset to the server and commit changes using updatebatch.

This works fine for me.