I've found that either one of these will lock the database:
mstrSQL = "PRAGMA locking_mode = EXCLUSIVE;BEGIN EXCLUSIVE;"
mstrSQL = "PRAGMA locking_mode = EXCLUSIVE;BEGIN EXCLUSIVE;COMMIT;"
and that closing the connection a little while later (eg. 0.25sec)
mcmd.Connection.Close()
releases it. I read in one place that you need a transaction eg. SELECT * FROM
Utilities WHERE RecNo = 1 for locking to occur, but this database locks
without one.
Jonathan
On 24 Apr 2013, at 11:58am, "J Trahair" <j.trah...@foreversoftware.co.uk> wrote:
> I had closed the connection after the COMMIT, but it works great if I don't.
Your problem is not with closing the connection but with the COMMIT. The BEGIN
goes with the COMMIT. When you go 'BEGIN EXCLUSIVE' you do have your exclusive
lock, but only until you have finished that transaction. And 'COMMIT' is one
way to finish a transaction, so the 'COMMIT' releases the lock. So your
procedure for locking a database for a quarter second is
BEGIN EXCLUSIVE
do anything you want here for a quarter second
COMMIT
You should definitely do the COMMIT eventually, of course. UNLESS you want to
cancel the transaction. But closing the connection plays no part in this.
Simon.
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