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Chris · Guest

Imagine if you will:

User opens Form1 and changes some data (which automatically starts a
transaction) but before commiting the changes he opens Form2 and changes
data (again automatically starting a transaction (which I guess is
considered nested)) but before commiting this he opens Form3 starting a new
transaction ......... Now the user accept changes in FormN......, Form3 and
Form2 but realises that he has messed up the data on Form1 so decides not to
save changes.

As I understand transactions the rollingback on Form1 will rollback the
already commited transactions on Form2, Form3...FormN, is this correct?

More to the point is there any way I can use the above model but start new
transactions that are independent of each other?

Cheers

Chris

PS Just to clarrify, code in the forms start the transactions when it is
detected that data has changed, this is because tracking changes with the
aim of performing a batch update on the forms data would be a massive job.

Jayme Jeffman Filho · Guest

Hi Chris,

The StartTransaction() is a TDatabase method which begins a transaction. If
you're using explicit transactions control, calling the StartTransaction
method, and the database on Forms 1, 2, 3.. are the same, the application
will raise an exception when you call StartTransaction() for the second time
without ending the previous one. So you can and should check if the Database
is in transaction mode through the TDatabase::InTransaction property and
make sure there is not any opened transaction before open a new one. BDE
does not support nested transactions, you can have a single one, so the
first call to the TDatabase::Rollback() or TDatabase::Commit() methods it
will end the current transaction no matter it has begun on another form
command.

It is a good advice do not allow the user open another database entry form
until he or she has done the task on the opened form.

Different users can update the same database tables as long as they are
working on different machines and the database instance is not the same.

HTH

Jayme.

"Chris" <chris (AT) REMOVEchrischfmousey (DOT) karoo.co.uk> wrote

Chris · Guest

Thanks for the info, it stopped me from continuing developing what would
have been a flawed process.

Chris

"Jayme Jeffman Filho" <jjeffman (AT) cpovo (DOT) net> wrote