Re: insert into problem

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#140

From: Wayne Niddery (TeamB)
Date: Mon, 09 Jun 2008 13:57

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"Isaac" <no@no.com> wrote in message news:484d2e33@newsgroups.borland.com...
>>
> Ok, can you please tell me what you mean by setting one of the fields to 
> itself


update mytable set myid = myid where myid = x

Locking as suggested by Bill requires the application to do two things:
1. Proper use of transactions
2. Handling the exception when the above SQL fails due to another user 
having it locked

Pseudocode would be:

    start transaction // must be read committed
    try
        update mytable set myid = myid where myid = x
        select max(itemnum) from mytable where myid = x
        newitemnum := fields[itemnum] + 1
        insert into mytable (myid, itemnum, ...) values (x, newitemnum, ...)
        commit transaction
    except
        // decide how to handle other user having this record locked already
        // could just go back around and try again since it should not be 
long
        // or can rollback transaction and inform the user to try again 
later
    end

-- 
Wayne Niddery - TeamB (www.teamb.com)
Winwright, Inc. (www.winwright.ca)

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Subject: Re: insert into problem
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