Transactions
lazarus / 16-Databases

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CraigC · 2026-04-01 20:42

If I call apply updates on one table while editing another, I can't
apply updates to the edited or inserted table. The transaction
component is not active. The dbgrid even shows that it isn't in browse
mode.

Any suggestions? Using Sqllite and Lazarus in Linux.

Craig

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cdbc · 2026-04-02 06:23

Hi
An active transaction excludes everything else from having an impact
on the database. It ensures you have write access to the data within
the db and keeps that state, until it's ended with a Commit (saved) or
Rollback'ed (canceled).
What you need to do, is write a 'Middle-tier' that handles locking and
transactions, which actually means, you keep the data in memory for
browsing at will, and then funnels changes to the db through one
transaction at the time, there will be some concurrency-questions in
that...!
HTH
Regards Benny

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CraigC · 2026-04-02 10:48

Thank you for the info.  Right off, I'm thinking memory tables then
loop through them to send each record to the server/database.

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cdbc · 2026-04-02 11:18

Hi
!!!BEWARE OF CONCURRENCY!!!
I.e.: You have to _lock_ a record in the db-table, if it has been
changed, so that another (say) form cannot update/change the same
record, before it has reread it from the db -- Oh the joy of multiuser
-- 
Otherwise you'll never know which change is persistent!!! 
Regards Benny