There are many non-obvious ways to return values from MySQL stored procedures, and each of them solves particular problems.

MySQL and MariaDB don’t allow optional parameters for stored procedures, nor procedures accepting any number of parameters. However, these features can be emulated by passing JSON documents. Let’s see how.

Changing triggers in production is problematic, because for a short time triggers will be missing, or inconsistent with each other. This article proposes a solution to resolve the problem.