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Transaction - End Transaction - Rollback
Message
From
12/04/2007 16:51:08
 
 
To
12/04/2007 12:04:15
Hans-Otto Lochmann
Dr. Lochmann Consulting Gmbh
Frankfurt, Germany
General information
Forum:
Visual FoxPro
Category:
Coding, syntax & commands
Miscellaneous
Thread ID:
01214857
Message ID:
01215238
Views:
16
This message has been marked as a message which has helped to the initial question of the thread.
Hello,

"The VFP help continues: "However, if you want to send transaction management commands directly to the backend, you can set the UseTransactions property of the CursorAdaptor object to False (.F.) and the CursorAdapter does not use transactions to send Insert, Update, or Delete commands....." Well this is not what I want to do, because I would like to use the transaction management functionality, if possible.
So please help me on that functionality."

this is exactly what you need, combined with "local" (FoxPro) transaction.

If you set "UseTransactions" to .T. each INSERT,UPDATE,DELETE command send from a CursorAdapter is wrapped in it's own transaction.
You want to update several CursorAdapter's in ONE transaction, correct?
Then you have to handle transactions manually -> set "UseTransaction" to .F.
on each CursorAdapter

some pseudo code to show the structure:
LOCAL lnCon, lbSuccess
lbSuccess = .F.
lnCon = loCA1.DataSource && get ODBC connection handle 
&& each CA must use this one connection to participate in the transaction
SQLSETPROP(lnCon,"Transactions",2) && enable manual transactions
BEGIN TRANSACTION && start transaction for local cursors only
DO CASE
 CASE !TABLEUPDATE(loCA1.Alias)
 CASE !TABLEUPDATE(loCA2.Alias)
 CASE !TABLEUPDATE(loCA3.Alias)
 OTHERWISE
  lbSuccess = .T.
ENDCASE

IF lbSuccess
  IF SQLCOMMIT(lnCon) != 1
    && AERROR(laOdbcError) && handle error
    ROLLBACK
  ELSE
    END TRANSACTION
  ENDIF
ELSE
  AERROR(laOdbcError) && handle TABLEUPDATE error
  SQLROLLBACK(lnCon) && rollback SQL Server transaction
  ROLLBACK           && rollback local cursors
ENDIF
SQLSETPROP(lnCon,"Transactions",1) && reset transaction setting on connection
We're using CA's exclusivly in our app.
Building base cursoradapter's for FoxPro data, and then subclasses for different SQL backends (if it's pure ANSI SQL the only thing we have to set in the subclass is "DataSourceType" to "ODBC"). Works really good. With remote views the app wouldn't have been possible since we have several m-n tables where we sometimes need to send UPDATE SQL commands from inserted rows, which is impossible with remote views, but with Cursoradapter's you can build whatever SQL commands you want in the BeforeInsert/BeforeUpdate/BeforeDelete events, very flexible.
They beat remote views in every aspect IMHO.

Regards
Christian
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