Database Design & Implementation Workshop 4 – Drawing ER Diagrams Draw Degree, Type & Participation diagrams that depict each of the following relatively simple ‘real-world’ situations:  A member of staff must work in a department, and there are many members of staff in each department. Several buses can park in the garage, and each bus may cover any number of routes. Each producer is in charge of several plays and there are several actors appearing in each play. At any one time an actor may be involved in more than one play. An operator can work on many machines and each machine has many operators. Each machine belongs to one department, but a department can have many machines.

ER Diagram Elements Entity Entity = a singular noun, enclosed in a box. Relationship = a solid line, with rounded ends. type => Type = a verb, or verb phrase. NB. MUST indicate the Type in BOTH directions. <= type 1 Degree = only two possibilities. M Compulsion = a vertical line, within an Entity.

Staff Department Work in => 1 M <= Has a) A member of staff must work in a department, and there are many members of staff in each department. Work in => Staff Department 1 M <= Has

b) Several buses can park in the garage, and each bus may cover any number of routes. 1 Bus Garage <= can accommodate 1 => Can be covered by May cover => M Route

c) Each producer is in charge of several plays and there are several actors appearing in each play. At any one time an actor may be involved in more than one play. 1 produces=> M Producer Play <=are produced by 1 is acted by=> M 1 M Actor Act/Play acts in=>

d) An operator can work on many machines and each machine has many operators. Each machine belongs to one department, but a department can have many machines. M m 1 1 <= has <= has dept Mac/op machine Belongs to => M Work on => 1 Example d operator