How do SQL queries return correct results? Databases for Developers #18

If your application is successful, you'll have many people using it at the same time.

But what happens when two or more people read and write to the same rows at the same time?

The SQL standard defines three problems that could happen:

Dirty reads
Non-repeatable reads
Phantom reads

This video explains what these are. And discusses how to manage these effects by setting the isolation level for your transaction.

Take the course:
https://devgym.oracle.com/pls/apex/dg...

Need help with SQL? Ask us over on AskTOM: https://asktom.oracle.com

Twitter:   / chrisrsaxon  
Daily SQL Twitter tips:   / sqldaily  
All Things SQL blog: https://blogs.oracle.com/sql/

============================
The Magic of SQL with Chris Saxon

Copyright © 2015 Oracle and/or its affiliates. Oracle is a registered trademark of Oracle and/or its affiliates. All rights reserved. Other names may be registered trademarks of their respective owners. Oracle disclaims any warranties or representations as to the accuracy or completeness of this recording, demonstration, and/or written materials (the “Materials”). The Materials are provided “as is” without any warranty of any kind, either express or implied, including without limitation warranties or merchantability, fitness for a particular purpose, and non-infringement.