Question

I have some sort of evaluating application in the making, it’s almost finished but I’m stuck with rather complicated SQL query.

To start with here are linked tables I am using (MySQL):

table1: USERS (list of users)

userID | name | surname | email

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table2: EVENT (list of events)

eventID | event_typeID | event_name | event_description

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table3: EVENT_TYPE (list of event types, each has number of points that a person gets if it’s involved in it)

event_typeID | number_of_point

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table4: USER_EVENT (list of user and event ID’s with multiplication factor)

user_eventID | userID | eventID | factor

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Function to get needed data is, let’s say: function getUsersWithPoints($number_of_points_for_threshold)

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What it needs to do is get name, surname, emailn total sum of points and all EVENTs user has been to for all users which have total number of points in events equal or greater than $number_of_points_for_threshold, but data must be taken indirectly, without getting it in another table.

Thanks in advance.

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Answer 1

First I’m assuming that USER_EVENT has the event_typeID as a column. I can’t where event_typeID is referenced anywhere else. Try something like this:

SELECT name, surname, email, sum(number_of_point) 
FROM user, user_event, event_type 
WHERE user.userID = user_event.userID AND user_event.event_typeID = event_type.event_typeID 
GROUP BY user.userID
HAVING sum(number_of_point) > :threshold
ORDER BY name ASC

Make sure you have indexes on user_event.userID and user_event.event_typeID a