Re: Select records that are not locked?

[Craig L Russell]

On Jan 6, 2006, at 9:30 AM, Bryan Pendleton wrote: Danny wrote: What I was after was a way to build a list of transactions that are available to edit for a user. What I don’t want in the list is any transactions that are currently being edited by another user. I think you should implement this notion of "transaction" within your application, and be careful not to confuse it with the lower-level DBMS concept of transaction. +1. This is an application-level concept that can be implemented using the techniques below. Craig That is, in your application, you should have a transaction table, and transactions should have a certain state, and a certain lifecycle, which you can define as appropriate for your application. Then, when a user is editing a transaction, you update the transaction state in your transaction table to reflect that this transaction is currently being edited by this user. And, when you want to build a list of transactions which are not currently being edited, you run a select statement which fetches the rows from your transaction table which are in the appropriate state. thanks, bryan P.S. Regarding the low-level DBMS transaction, I agree with what others have already said: keep them short and focused; don't hold them open across UI think periods. Fetch some data from the database, update things as necessary to reflect that a user is currently working with this data, then commit that DBMS transaction. Later, when the user issues some command in the UI, use a separate DBMS transaction to return to those records and process them accordingly. Craig Russell Architect, Sun Java Enterprise System http://java.sun.com/products/jdo 408 276-5638 mailto:[EMAIL PROTECTED] P.S. A good JDO? O, Gasp!

smime.p7s
Description: S/MIME cryptographic signature