Mysql info

Gick igen några SQL-frågor

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