The FACTS define the Business Rules ...

1. What are the 'Things of Interest' in the Scope to be modelled ...

• Person (Persons_id, Person_name, Person_address, Person_phone)
• Instrument (Instrument_id, Instrument_name, Instrument_type)
• Proficiency (Persons_proficiency, Person_id, Instrument_id)
• Band (Band_id, Band_name, Band_contact_peson_id)
• Band_Member (Band_id, Person_id)

2. How are these 'Things of Interest' related ? ...

• An Instrument is always of one and only Type.
• A Person can play one or many Instruments, if the Contact Person always plays an Instrument.
• A Person can play zero or many Instruments, if the Contact Person could be a member who does not play an Instrument, such as a Band Manager or Agent.
• A Person always has a specified Profiency Level in an Instrument.
• A Person can be in zero or many Bands.
• A Person has a specified Role in a Band, such as Contact Person, or Band Member.

3. What do we know about the 'Things of Interest' ? ...

In the Data Model, an 'id' field, such as person_id, is a generated integer, without any meaning in itself, and is used as a surrogate key.
A 'code' field is an abbrevation of a name or description, and used because the volumes of data are smaller, and do not need to be generated dynamically.

• A Band has :-
  1. A Band Code
  2. A Band Name
  3. The Date Started, if known.
  4. The Date Disbanded, which will usually be in the future, and unspecified.
• An Instrument has :-
  1. An Instrument Code
  2. An Instrument Name
• A Person has :-
  1. An ID.
  2. A Name
  3. An Address
  4. A Phone.
• A Role is Reference data ans has :-
  1. A Role Code,(e.g. 'CONTACT')
  2. A Description