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[DMDB] Learnings from practice exams, plus some more tips and tricks

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semester4/dmdb/parts/00_relational-model_logic/00_model/01_keys.tex
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\subsubsection{Keys}
\label{sec:relations-keys}
\inlinedefinition[Candidate Key] The minimal set of fields that identify each tuple uniquely (non-duplicate attributes (fields) typically)
\inlinedefinition[Candidate Key] The \bi{minimal} set of fields that identify each tuple uniquely (non-duplicate attributes (fields) typically).
In other words, it is the minimal set such that for its closure $F+$ and the relation $\cR$ that it belongs to, $\forall y \in F+ \implies y \in \cR$.
\inlinedefinition[Primary Key] A single candidate key, i.e. just a single field.
We mark the primary key using \underline{underlining} in visual \glspl{schema}.