Lock something about mySQL database!!!

[Anon]

Hi all,
First,I want to thank all who have helped me.
This time I want to ask how I can lock some records in my database. I'm doing a groupware project, I hope when someone is updating the mySQL database, other users can only read but not update. Do I have any way to lock the record, then I can keep my database consistant?

Regards Jane

[Anon]

Yes you can lock tables in mysql. Do you have the manual?

[Anon]

MySQL can only lock whole tables,making them read-only etc. untill the lock is removed.

If you want to lock seperate records, you'll have to add some sort of locking mechanism yourself.
I reccomend adding a field named something like MEDIUMINT "locked_by"
This field could then contain the userid of the user who locked the record.

To stop other people from updating the record, you could add a new condition to your sql update statement;
where ... and ... and (locked_by=0 or locked_by=userid);

Added bonus is that you allways know who locked the record, so you can give an error message like:
"Sorry, can't update this information, user <insert name here> is updating it"

[Anon]

But, What is the mysql's reaction if user A locked one table but close her browser and never release the lock?

Does that mean no one can update the data any more?