RE: Multi-User Update Problem

"Bastien Koert" <bastien_k@xxxxxxxxxxx> · Mon, 29 Nov 2004 10:22:24 -0500

Its a tough one. My personal fav is to mark the record as locked by changing 
a field called 'locked' from 0 to 1. Check for this when extracting the 
record and if is present, alert the user this record is locked (if you want 
to get fancy you could even track who locked it and the tell the user that) 
and show a non-updatable form of the page (either with the fields as 
readonly or by creating some kind of view only page where the data is simply 
echoed out). If you want to get REALLY out there, you could track who 
requested the locked record and notify them when it was released(by the 
original requestor submitting the form). The possibilities are endless

The other option is to create/write an entire concurrency module that will 
store the record in a separate entity (another table or session object)  and 
then compare any changes made upon submission. I have seen this but I don't 
really like it, since the ultimate choice is left to the user as to what 
data is correct.

Bastien

From: "SCALES, Andrew" <Andrew.SCALES@xxxxxxxxxxxxxxxxx>
To: php-db@xxxxxxxxxxxxx
Subject:  Multi-User Update Problem
Date: Mon, 29 Nov 2004 11:16:08 -0000

Hello,

Does anyone know a good way of locking out access to a record on a MySQL

database when someone has the update page open?

The problem is that we have a local intranet site which is accessed by

members of different departments. Now at the moment when someone loads the

page all of the data is pulled into the form, and then when they submit, 
all

of that data is passed back to the database, including anything they 
haven't

changed.

What we are trying to avoid is situations where for example someone leaves

the form open on their computer and goes away for lunch. In the meantime

someone else at a different station makes changes to the form. Then when 
the

first person comes back from lunch, they submit the form, thereby writing

over all of the second person's changes with the old data.

Does anyone know of a good way to solve or work around this problem? We 
have

thought about setting a flag on the database whenever someone pulls down 
the

data, however if their browser crashes or they shutdown with the window 
open

then this is going to leave the data locked.

Thanks very much,

Andy

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