[DMDB] relational model, relational algebra, SQL very basics

semester4/dmdb/parts/01_sql/00_intro.tex

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+\acrshort{sql}, or unabbreviated, \acrlong{sql}, is a \gls{declarative} programming language, used to describe and operate on databases.
+
+This is is the point to mention \hlhref{https://xkcd.com/927/}{xkcd standards comic}, because, as is the case with almost any standard,
+people deviate from it and new standards form.
+
+Even though \textit{most} \acrshort{sql} databases support the standard SQL operations, many have added a lot of features on top.
+
+\sql\ is split up into the query language itself, used to operate on data, as well as the Data Definition Language,
+used to create, modify and delete schemas.