I agree with Jason's assertion 100%. Your best bet on the web is record versioning.
Larry On 11/1/05, Jason King <[EMAIL PROTECTED]> wrote: > This isn't a struts question so much as a persistence layer question. > There are several approaches you can use depending on your data and your > users. > For infrequently updated tables you can hope for the best and probably > be safe. > If you're in an EJB world the EBJ layer takes care of that (I think). > If you're using JDBC you can: > a) implement a last_updated column and a trigger to populate it in your > tables (assuming the db supports it) and only do an update if the > current last_updated matches the one with the new values (that means > user b errors out). He won't be thrilled, but you'll have no lost updates. > b) Save old values (possibly in a session-level object) and only > perform the update if all the current row values match the saved ones > from the session. This works for trigger-impaired databases, but also > causes User B to get an error message. > Using Ibatis a similar approach to raw JDBC should work. Never having > used Hibernate I can't tell you if it has any provisions to avoid the > "lost update" problem you described. I can fairly confidently state > that you won't be able to solve the problem via record-locking. Given > the largely stateless nature of web applications and the likelyhood of > connections dropping, you'd be setting yourself up for hell if you tried > to maintain a database transaction across multiple submits. > Murray Collingwood wrote: > > >Hi all > > > >As long as I have been on this list I have never heard anybody discuss > >record locking. > >The scenario is very simple: > > > >1. User A clicks an "edit" option to edit a record. > >2. While user A is editing the record user B clicks the same "edit" option > >3. Both users are now editing the same record (or so they think) > >4. User A clicks "save" and the record is updated and displays the changes > >made by > >user A - user A is happy > >5. User B clicks "save" and these changes overwirte the changes made by user > >A, > >however user B doesn't know this and the changes made by user B appear. > > > >Sometime later user A realises that the changes made have disappeared and > >gets > >angry and begins throwing large objects around the room and making lots of > >loudish > >gutteral noises in an attempt to disperse inner emotional anxiety. > > > >Well, you get the picture. > > > >Q. Does Struts assume that the developer will code in the appropriate record > >locks in > >the database? > > > >Q. Does anybody actually do this? > > > >Q. How? What type of record locking do you use? > > > >TIA > >mc > > > >FOCUS Computing - web design > >Mob: 0415 24 26 24 > >[EMAIL PROTECTED] > >http://www.focus-computing.com.au > > > > > > > > > > > > > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] > > --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
