Re: oracle - mysql comparison

From: Daniel Morgan <damorgan_at_x.washington.edu>
Date: Tue, 20 Jul 2004 19:51:00 -0700
Message-ID: <1090378283.651396@yasure>

Volker Hetzer wrote:

> "VC" <boston103_at_hotmail.com> schrieb im Newsbeitrag news:RfdLc.109372$WX.92600_at_attbi_s51...
> 

>>Here's another textbook example for you:
>>==
>>There are two linked accounts (id=1 and id=2) in a bank. A transaction
>>might look as follows:
>>
>>== withdraw from 1
>>select amount into x from accounts where id=1
>>select amount into y from accounts where id=2
>>if x+y >= withdrawal then update accounts set amount=amount-withdrawal
>>where id=1
>>commit
>>=====
>>
>>Any commercial locking scheduler will handle the scenario correctly. Oracle
>>won't.

> 
> Sorry for butting in but I'm just trying to learn here, so what would go wrong?
> And what about "select for update" in oracle? It's supposed to lock the rows it hits.
> 
> Lots of Greetings!
> Volker

You are correct and VC, as I earlier stated to him, is demonstrating far less than a robust understanding of transaction processing: Lots of smoke but no fire.

Daniel Morgan Received on Tue Jul 20 2004 - 21:51:00 CDT