Design Pattern for Custom Fields in Relational Database

Question

I have assigned a task to create (relatively) simple reporting system. In these system, user will be shown a table result of report. A table has some fields and each field g

Answer 1

Use MariaDB, with it's Dynamic Columns. Effectively, that lets you put all the miscellany columns into a single column, yet still give you efficient access to them.

I would keep a few of the common fields in their own columns.

More discussion of EAV and suggestions (and how to do it without Dynamic Columns).