In this guest video, Natalka shows how you can use SQL to traverse a linked list of co-ordinates. She then demonstrates how to remove points that are not on a corner. She does this using the analytic functions lag and lead. For more SQL content from Natalka, head to her blog http://rdbms-insight.com/ ============================ 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.