如何确保仅“应用”了一个更新？

Question

Let's say I define a table like so:

create table anonymized_example(
  id bigint IDENTITY(1,1) PRIMARY KEY,
  status varchar(50) not null,
  other_columns varchar(50));

Now, sometimes to threads in a cluster may want to update this table at the same time. My idea is to run a query like this:

update reservation_proxy_order,
set status='WORKING_ON_IT',
where id=?,
and status <> 'WORKING_ON_IT';

As far as I understand, this means that one of the threads will get to update first, and return out that 1 row was updated, and the other(s) will report that they updated 0 rows. And that's great. Now one thread in the cluster will start doing it's thing, and the rest will be left alone.

However, there's something that doesn't sit quite right with me. Is this a valid way to do this? Or are there better ways that should be considered?

Answer 1

Yes and status <> 'WORKING_ON_IT should assure that only the first update is applied. (0 row(s) affected) means nothing was changed.

Test for yourself by running it multiple times.