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Nearly 20% of Microsoft SQL Servers running have passed end of support
(www.theregister.com)
This is a most excellent place for technology news and articles.
There are people who pay for MySQL and Mongo. And even MariaDB. All of them have enterprise versions of their software.
And how many years do they support a specific release before making you upgrade.
Looks like MySQL standard releases are one year and LTS releases are 5 or up to 8 with extended support.
So somewhat similar to Microsoft