What is database compatibility level in SQL Server, how dangerous is it to change?

Question

SQL Server

I wanted to use OPENJSON on MS SQL Server 2016, but I can't find it. It turned out that I needed compatibility level under 130.
I looked in sys.databases - on the database I need it costs 100. 130 is only for service databases.
How dangerous is it to change this compatibility level from 100 to 130 ?

Answer 1

How dangerous is it to change this compatibility level from 100 to 130?

No down compatibility. That is, there will be no possibility to change back.
Backups are limited upward compatible, for example, MS SQL 2000 will not be restored in MS SQL 2016, only in 2008.
More details msdn.microsoft.com