database design - Please critique E-R diagram of datamodel -

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i'm building data model website of student club @ university , need feedback on have far.

every term students become members paying membership fee. membership fee entitles them attend club's activities less social events during term. attend these social events required purchase ticket.

the club's activities involved courses of 8 10 weekly classes, workshops, , aforementioned events.

we able model members every term , track registration , attendance courses ( registration ), individual classes ( attendance ), workshops ( attendance , registration), , events (attendance , registration).

we want able see member of executive involved in activity.

we want executive able upload articles (text), pictures, music, , video , control has access these items. used group solution because think granting access @ user/piece of content level tedious.

please take , give me feedback. i'm trying design model easy maintain , adapt new requirements , robust, , flexible when comes modelling club , member activity.

the password hash part of student entity. it's not showing on digram.

you can find diagram below.

edit1:

added legend.

at top, rectangle around student--membership--term called aggregation. means when used in relationship registration, example, can @ aggregation entity primary key (student_id, term).

edit2: triangle isa label on denotes specialization of top entity child entities. when translating schema can choose create relation each, or children.

one thing jumped out @ me. although activities have addresses, people don't. seems really, odd.

i'd say, "activities happen @ 1 or more locations". activities don't have addresses @ all, location or locations do. also, depending on how define "activity", single activity might take place @ different locations @ different times. so, example, if "group protest of war in iraq" activity, might take place @ courthouse today, , @ library tomorrow. of course, 2 events might 2 different activities.

what address use online activities?


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