tex-projects/LaTeX-examples
2
0
Fork 0
mirror of https://github.com/MartinThoma/LaTeX-examples.git synced 2025-04-25 06:18:05 +02:00
Code Activity

Merge pull request #11 from taikano/patch-5

Browse source 
Korrektur + Ergänzung
This commit is contained in:
Martin Thoma 2013-07-30 03:58:02 -07:00
commit c3f55e2d1e
1 changed files with 23 additions and 2 deletions
Download patch file Download diff file Expand all files Collapse all files

25
documents/musterloesung-db-2012-09-24/d2c2.sql
View file

@ -1,13 +1,34 @@
SELECT f1.person2, f2.person2
FROM (
SELECT person2 FROM FriendshipSymmetric WHERE person1 = <id>
SELECT * FROM FriendshipSymmetric WHERE person1 = <id>
) f1
JOIN ON
(
SELECT person2 FROM FriendshipSymmetric WHERE person1 = <id>
SELECT * FROM FriendshipSymmetric WHERE person1 = <id>
) f2
EXCEPT
(
SELECT * FROM FriendshipSymmetric
)
WHERE f1.person2 != f2.person2
Ohne EXCEPT (da ich mir nicht sicher bin, ob es nun SQL-Standard
ist oder nicht, z.B. SQLite kenn kein EXCEPT, auf einer Übersicht
stand es aber bei SQL89 angehakt dabei).
Hinweis: NOT EXISTS ist True, gdw die Unterabfrage genau 0
Zeilen enthält.
SELECT f1.person2, f2.person2
FROM (
SELECT * FROM FriendshipSymmetric WHERE person1 = 4
) f1
JOIN
(
SELECT * FROM FriendshipSymmetric WHERE person1 = 4
) f2 ON f1.person1 = f2.person1
WHERE f1.person2 != f2.person2
AND NOT EXISTS
(
SELECT * FROM FriendshipSymmetric f WHERE f.person1 = f1.person2 AND f.person2 = f2.person2
)