Erik schrieb:
> Hi,
> I plan to develop an application that is somewhat like a spreadsheet
> with cells containing formulas. When a cell value is changed, things
> must be updated. But the formulas can contain database queries, which
> means that the cell has to be notified when the database changes in such
> a way that that the result of the query changes. How is this done? I
> would really like to avoid recalculating the whole thing for each change
> to the database.


In the moment I only know one DBMS which has this feature and this is
Postgres. Look in the Postgres-Docu and have a look at NOTIFY and
LISTEN. But to use this feature you can not use the
QT-Database-Extensions. You have to use libpq.

http://www.postgresql.org/docs/8.1/i...ql-notify.html
http://www.postgresql.org/docs/8.1/i...ql-listen.html
http://www.postgresql.org/docs/8.1/i...pq-notify.html

Stefan

P.S.: I've never used listen and notify with the C-Library, so I can't
give you more help on this.

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