Database concurrency/ Data integrity

Hi!

I'm creating a portal application with UIDesigner. I'm able to load a table with the results of a Rest API query.
Once I've selected a row I want to start a task for that particular item. I can do it without problems but, how can I prevent other users not to use that record? Is there any trick or recommendation? Can I send some kind of signal to other portal users not to use that record? Do I have to block in any way that record on the database? How can achieve it?

Thanks in advance!
Dave