[DMDB] Basics of first and second normal form

semester4/dmdb/parts/02_theory-background/01_normal-forms/01_first-nf.tex

@@ -1 +1,11 @@
 \subsubsection{First Normal Form}
+In the first normal form, only atomic domains are allowed.
+
+\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.

semester4/dmdb/parts/02_theory-background/01_normal-forms/02_second-nf.tex

@@ -0,0 +1,10 @@
+\subsection{Second Normal Form}
+The two dependencies $\{ \text{Legi}, \text{Nr} \} \rightrightarrow \{ \text{Name}, \text{Semester} \}$,
+$\{ \text{Legi} \} \rightrightarrow \{ \text{Name}, \text{Semester} \}$ state the following:
+
+\begin{itemize}
+    \item Legi determines the name and semester of a student.
+    \item The first map has to happen, even though mapping $\{ \text{Legi}, \text{Nr} \}$ to $\{ \text{Legi} \}$ would be enough. We thus will have redundancy.
+          However, this is the exact relationship that the table is meant to capture
+          Thus, $\{ \text{Name}, \text{Semester} \}$ should not be in the table at all.
+\end{itemize}