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<p>Seite erstellt</p> <p><b>Neue Seite</b></p><div><br /> Ein SQL-Join ist eine Abfrageoperation in relationalen Datenbanksystemen.<br /> Dabei werden mindestens zwei Tabellen der Datenbank verknüpft und anhand der Abfrage gefiltert.<br /> <br /> <br /> <br /> <br /> {|<br /> |-<br /> ! inner Join<br /> |-<br /> | SELECT column_name(s)<br /> |-<br /> | FROM table1<br /> |-<br /> | INNER JOIN table2<br /> |-<br /> | ON table1.column_name = table2.column_name;<br /> |}<br /> <br /> <br /> <br /> {|<br /> |-<br /> ! full outer Join<br /> |-<br /> | SELECT column_name(s)<br /> |-<br /> | FROM table1<br /> |-<br /> | FULL OUTER JOIN table2<br /> |-<br /> | ON table1.column_name = table2.column_name<br /> |-<br /> | WHERE condition table1;<br /> |}<br /> <br /> <br /> {|<br /> |-<br /> ! right Join<br /> |-<br /> | SELECT column_name(s)<br /> |-<br /> | FROM table1<br /> |-<br /> | RIGHT JOIN table2<br /> |-<br /> | ON table1.column_name = table2.column_name;<br /> |}<br /> <br /> <br /> {|<br /> |-<br /> ! left Join<br /> |-<br /> | SELECT column_name(s)<br /> |-<br /> | FROM table1<br /> |-<br /> | LEFT JOIN table2<br /> |-<br /> | ON table1.column_name = table2.column_name;<br /> |}<br /> <br /> <br /> Detailliert auf:<br /> <br /> https://www.w3schools.com/sql/sql_join.asp<br /> <br /> und<br /> <br /> https://de.wikipedia.org/wiki/Join_(SQL)#FULL_OUTER_JOIN<br /> <br /> <br /> Weiterführend in der Mathematik &quot;Mengenlehre&quot;:<br /> <br /> https://www.mathebibel.de/mengenlehre</div>

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