8. You have been asked to develop a preliminary ERD for a symphony Orchestra. So far, you have uncovered the following Entities:
· CONCERT SEASON. The Season during which a series of concerts will be performed. One of the attributes you have chosen is Opening_Day, which includes Month, Day, and Year.
· CONCERT. This is a given performance, which consists of one or more compositions. Some of the attributes decided upon include Concert_No and Concert_Date, which consists of Month, Day, Year and Time. Each Concert is generally, although not always, perfomed on more than one concert date.
· COMPOSITION. Each concert may have may compositions performed, although sometimes, only one composition is performed. Attributes decided upon include Composition_ID, Composer_Name, Composition_Name, and Movement_ID (Which is a composite attribute consisting of Movement_Number and Movement_Name). Many, but not all, compositions have multiple movements.
· CONDUCTOR. Although there is a principal conductor, who generally conducts the symphony, there are frequent guest conductors. This entity includes Conductor_ID and Conductor_Name.
· SOLOIST. The symphony frequently, although not always, employs guest soloists. These are identified by Soloist_ID and Soloist_Name.
During further investigation, you discovered a number of additional considerations:
· During a concert season, there are one or more concerts scheduled. A particular concert is scheduled only once in a season.
· The Concert includes the performance of one or more compositions. However, A composition may be performed at one or more concerts, or may not be performed all season.
· For each concert, there is one and only one conductor. A conductor may conduct any number of compositions, or may not conduct that season.
· Each composition may require one or more soloists, or may not require a soloist. A soloist may perform one or more compositions at any given concert. The symphony wishes to record the date when a soloist last performed a given composition (Date_Last_Performed).