Question

Spot the entities, entities instance attributes and relationship. Make an ERD of it
A) CONCERT SEASON - The season during which a series of concerts will be performed. The identifier is a text
field containing the Season in the form 2002-03. We also want to know the number of advance tickets sold, total
number of tickets sold and total incomes and expenses for the season.
B) CONCERT - A given set of one or more compositions to be played. The identifier is a Concert_Number, which
starts at 1 and runs sequentially. Another important feature of a Concert is a Performance, which consists of a
performance date (Month, Day, Year) and time. Each concert typically has more than one performance. We also
want to know the paid attendance for a given performance. (So should Performance_Date be an attribute or an
entity?)
C) COMPOSITION - Composition (musical work such as a Beethoven Symphony or Rossini Overture) to be
performed at each CONCERT (or Performance?). The identifier is a Composition_ID, which consists of a
Composer_Name and Composition_Name. Another feature of a composition is a Movement_Id, which consists of
two parts; a Movement_Number and Movement_Name. Many, but not all, compositions have multiple movements.
D) CONDUCTOR – The person who will conduct the concert. The identifier is Conductor_ID. Another attribute is
Conductor_Name and dates of all performances given by the conductor.
During further discussions additional business rules (constraints) were identified.
1. A concert season schedules one or more concerts. A particular concert is scheduled for only one season.
2. A concert includes the performance of one or more compositions. A composition may be performed at one or
more concerts, or may not be performed.
3. For each concert there is one conductor. A conductor may conduct any number of concerts performances, or may
not conduct any concerts.
4. Each composition may require one or more soloists, or may not require a soloist. A soloist may perform one or
more compositions at a given concert, or may not perform any composition. The symphony orchestra wishes to
record the date when a soloist last performed a given composition (Date_Last_Performed).

Answer 1

An Entity Relationship Diagram (ERD) is a snapshot of data structures. An Entity Relationship Diagram shows entities (tables) in a database and relationships between tables within that database. For a good database design it is essential to have an Entity Relationship Diagram.