Gilles Ganault <gilles.ganault-jG/[EMAIL PROTECTED]>
wrote:
I'd like to use a timestamp column in each table to keep track of
when a column was last updated, so that a user can be notified of a
problem
when trying to updated a record that has already been updated by
another
user while the first user was still working on the original data.
In www.sqlite.org/lang_conflict.html, I read about the "UPDATE OR
ROLLBACK" instructions, so tried the following using Todd Tanner's
VBified
SQLite DLL... but am not notified of anything special: SQLite doesn't
return
any error, and just reports that no row matches:
'row already updated by someone else, so timestamp=2 -> no row
actually matches constraint
mQuery = "begin;"
mQuery = mQuery & "update OR ROLLBACK mytable set name='bart',
timestamp=2 where id=1 and timestamp=1;"
The conflict resolution clause ("OR ROLLBACK" in your case) kicks in,
unsurprisingly, when there is a conflict - e.g. when an update would
violate a uniqueness or CHECK constraint. It is a normal case, and not a
conflict, when the condition in the WHERE clause simply selects zero
rows.
See sqlite3_changes:
http://sqlite.org/capi3ref.html#sqlite3_changes
Igor Tandetnik
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