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SS2026/Datenbanken und Informationssysteme/SQL/DQL Data Query Language SQL.md

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+### SELECT
+```
+SELECT MatrNr, Name, Semester from Student
+```
+
+Spalte umbenennen
+`SELECT MatrNr AS InsassenNr from Student`
+
+Keine Duplikate
+`SELECT DISTINCT Semester AS Jahrgänge from Student`
+
+### WHERE
+
+```
+SELECT * from Student WHERE Semester = 2
+---
+SELECT * from Student s WHERE s.Semester = 2 AND s.Name='Byleth' 
+```
+
+#### Anatomie einer WHERE Klausel
+Vergleichsoperatoren: <,>,=,<=,>=,<>
+BETWEEN
+LIKE
+IS NULL / IS NOT NULL
+AND, OR, NOT
++,-,\*,/
+IN, NOT IN, $\theta$ ANY, $\theta$ ALL, EXISTS mit $\theta$ = Vergleichsoperator