\subsubsection{First Normal Form}
In the first normal form, only atomic domains are allowed, i.e. keys are not allowed to be arrays.

\inlineintuition This makes the concept of a key easier to define, or well defined

Some \sql\ flavours support arrays. However, the semantics and the support varies

This can come in handy to solve one to many relationships, but what if many different persons have the same elements there?
This can cause some issues when updating.

Arrays are very tempting to use if we have an unknown and variable number of different data points for a field.
