I'm looking for some help in decomposing a couple of many-to-many relationships for a piece of coursework...

These are the entities and their attributes I've established from the requirements specification:
and here's the un-decomposed ERD I've made using this info.

The spec states that each course is delivered by one staff member, but I've assumed that any staff member can deliver more than one course, hence the one-to-many relationship between those two entities.

However, what's completely stumped me is the relationship between Course and Delegate, as the course is obviously attended by many delegates, and the spec states that a delegate may attend multiple courses. This also applies to Invoice and Delegate, as a Delegate could potentially receive multiple Invoices, and Invoices are sent to multiple Delegates.

The question states that the M:M relationships should be "replaced with new entity types and relationships", but my (hair-brained) attempts to do so just don't seem right.


Tell me, am I looking at this all wrong? Any help regarding this would be hugely appreciated.

Though I don't know exactly how to read the diagrams,
if entity A and entity B has a many to many relationship, like...
A(primary key: PK_A) (many)<--->(many) B(primary ke: PK_B)

make a new entity(say, A_B) for the M:M relationship, like...
A <---(foreign key: PK_A)--- A_B(primary key: (PK_A, PK_B) ) ---(foreign key: PK_B)---> B

Do you understand there need to be an Entity that ESTABLISHES Those Relationships?

STAFF 1====M Courses

Such that

Staff
Staff ID
Name
ect

Course
CourseID
Course Name
ect

Staff_Teaching_Course -- Your NEW Entity
StaffID
CourseID

Not that hard