Sw4 > Sql > Manual Transactions
If you are working with an RDBMS that supports COMMIT and ROLLBACK you may want to make use manual transactions when you are saving batches of records, or a sequence of inserts where a parent records is inserted immediately followed by one or more child records.
In these situations if you set the session object $transactionmode to kSessionTranManual at the start of the batch; you can issue a $rollback at the end if an error occurs and the database will undo the database writes, or if all goes well you can issue a $commit and all the database writes are fully saved by the database.
The control point for the decision to $commit or $rollback transactions is outside of the table class. If you are using manual transactions be sure to set the pbIssueSaveListWork parameter of $doworkBatch to kFalse, and then remember to send a $savelistwork message to your smartlist when you commit the transactions.
Always be sure to set the $transactionmode back to kSessionTranAutomatic at the of the method.
The following sample code shows how you might use manual transactions in your code:
; Store the current $transactionmode, set to manual transactions.
Calculate StartMode as db1sess.$transactionmode
Do db1sess.$transactionmode.$assign(kSessionTranManual)
; Insert parent list records.
Do ParentList.$doworkBatch(kFalse) Returns FlagOK ;; (bIssueSaveListWork)
If FlagOK
; Insert child records.
Do ChildList.$doworkBatch(kFalse) Returns FlagOK ;; (bIssueSaveListWork)
End If
If not(FlagOK)
; Something went wrong. Rollback all database changes.
Do db1sess.$rollback()
Else
; All went well, commit the database changes and make the history list the same as the normal list.
Do db1sess.$commit()
Do ParentList.$savelistwork()
Do ChildList.$savelistwork()
End If
; Always set the transaction mode back to its original setting.
Do db1sess.$transactionmode.$assign(StartMode)
Quit method FlagOK