Question

Im storing columns in database with users able to add and remove columns, with fake columns. How do I implement this efficiently?

Answer 1

The best way would be to implement the data structure vertically, instead of normal horizontal.

This can be done using something like

TableAttribute
    AttributeID
    AttributeType
    AttributeValue

This application of vertical is mostly used in applications where users can create their own custom forms, and field (if i recall corretly the devexpress form layout allows you to create custom layouts). Mostly used in CRM applications, this is easily modified inproduction, and easily maintainable, but can greatly decrease SQL performance once the data set becomes very large.

EDIT:

This will depend on how far you wish to take it. You can set it up that it will be per form/table, add attributes that describe the actual control (lookup, combo, datetime, etc…) position of the controls, allowed values (min/max/allow null).

This can become a very cumbersome task, but will greatly depend on your actual needs.