Setting the database to the right compatibility level is very important as it can have negative impact on the performance and behavior of your databases. I’ve seen many customers upgrade their SQL Servers from older versions to newer but forget to upgrade the compatibility of their databases. This means that even though you have an upgraded version of SQL Server, your database cannot benefit from any new or enhanced features of SQL Server since your database is running on an old compatibility level.

Incompatible database could also lead to inefficient query plans. Therefore, it is important that you upgrade the compatibility of databases right after the upgrade or right after you restore the database from older version to a newer version.

This script can help scan thru all the databases and provide you with a list of current and recommended database compatibility level.