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mysql_info [2009-09-30 13:02]
Joakim Forsgren created 		mysql_info [2010-12-10 10:33]
Joakim Forsgren
Line 1: Line 1:
 ====== Mysql info ====== ====== Mysql info ======
-Gick igen en SQL-fråga +Gick igen några SQL-frågor 
-<code mysql>+<code>
 SELECT *,COUNT(ItemID) as Number FROM Threads LEFT JOIN Items USING(ThreadID) GROUP BY (ThreadID) SELECT *,COUNT(ItemID) as Number FROM Threads LEFT JOIN Items USING(ThreadID) GROUP BY (ThreadID)
 +
 +SELECT lab5_Threads.*,lab5_Users.*,COUNT(ItemID) as NumItems FROM `lab5_Threads` INNER JOIN `lab5_Users` USING(UserID) LEFT JOIN `lab5_Items` USING(ThreadID) GROUP BY ThreadID
 +
 +
 +# För att ta bort, gör först en korrekt select
 +SELECT * FROM `lab5_Threads` RIGHT JOIN lab5_Items USING(ThreadID) WHERE Thread IS NULL
 +# sen ändrar man den till en delete
 +DELETE lab5_Items FROM `lab5_Threads` RIGHT JOIN lab5_Items USING(ThreadID) WHERE Thread IS NULL
 </code> </code>