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Robert Cerny
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 Posted: Mon Sep 15, 2003 5:41 pm Post subject: Re: Handling multiple users |
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Use a trigger to do validation or a stored procedure to do validation and
update.
--
Robert Cerny
DelphiShaman
"Kris" <noreply (AT) nomail (DOT) com> wrote
| Quote: | Suppose I have a multiuser app accessing a SQLServer database, and when a
user want to update some data, certain condition A must be valid (for
example, some query must return no records).
Suppose condition A is valid:
Query.Open;
if Query.RecordCount = 0 then <<-- A is Valid
begin
// Let the user update the database
SomeTable.Edit;
...........
SomeTable.Post; /// <<-- After post is executed, A is no longer valid
end;
Now: suppose that after RecordCount = 0 is checked, and just before the
.Post, A is no longer valid because another user made modifications to the
DB: then the app will be in an invalid state.
How to solve this problem? With transactions? Locking exclusibly the table
where Query consults?
Thanks
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