No, Daniel. This operation is atomic ( can not be separated into smaller
parts ).
This is the correct way to do updates without user locking.
The update thread will automatically lock the file during the update
so no other process can modify the data.
Daniel B I wrote:
>
> Hello,
> if there is a MYSQL developer member (or guru), I would
> like to ask if there is possible that another query modify
> a field between the detection of a target row and the changes
> made to it, by an update query.
>
> Let me explain myself a little: suppose we have an update query, like
> this:
>
> UPDATE table SET field = field-1 WHERE field = 5
>
> my question is: when this command is issued,
> is it possible for another thread to modify the field's value,
> **between the detection of a matching row and the real update** ?
> If all occurs before or after the update, no matter, but if this can
> occur, this UPDATE command is not sure, because I exepect to have
> a '4' in that field and instead I may have a '3'.
>
> It's very important to me, because I plan to use it in a production
> environment, as a simple transaction method, and I need to know
> this, as exactly as possible.
>
> Thank you so much,
> Daniel BI
>
> ---------------------------------------------------------------------
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