What are the three properties that every relationship should have?
– Transferability, degree, name
Name, optionality, degree (*)
– A UID bar, a diamond, an arc
– Name, optionality, arcs
2. Relationships can be either mandatory or optional. True or False?
3. In a business that sells computers, choose the best relationship name from CUSTOMER to ITEM (computer, in this case).
Each CUSTOMER must be the buyer of one or more ITEMS. (*)
– Each CUSTOMER must be the seller of one or more ITEMS.
– Each CUSTOMER may be the maker of one or more ITEMS.
– Each CUSTOMER may be the producer of one or more ITEMS.
4. Relationships always exist between
– 3 or more entities
2 entities (or one entity twice) (*)
– 2 attributes
– 3 or more attributes
Test: Quiz: ER Diagramming
1. Attributes are written inside the entity to which they belong. True or False?
2. Entity boxes are drawn as
Soft Boxes (*)
– Hard Boxes
– Bold Circles
– Normal Circles
3. Entity names are always plural. True or False?
4. Which symbol is used to indicate that a particular attribute is optional?
5. On an ER diagram which symbol identifies an attribute as part of a unique identifier.
6. Consider the recommended drawing conventions for ERD’s. Indicate which of the following accurately describes diagramming conventions for entities and attributes:
– The * means that an attribute is optional and entity names should be plural verbs
– The ‘o’ means that the attribute is optional and entity names should be plural verbs
The * means that an attribute is mandatory or required and the entity name should be singular (*)
– The ‘o’ means that the attribute is mandatory or required and the entity name should be a singular noun
Test: Quiz: Speaking ERDish and Drawing Relationships
1. Two entities can have one or more relationships between them. True or False?
2. After looking at the diagram, choose the sentence below that could be “read” from the existing relationship (even though you’re missing relationship labels!)
– Each Student must have one or more Activities.
– Each Activity may be performed by one or more Students.
Each Student may participate in one or more Activities. (*)
– Each Activity must belong to one and only one Student.
3. When reading a relationship between 2 entities, the relationship is only read from left to right. True or False?
Test: Quiz: Matrix Diagrams
1. A Matrix Diagram will help you with all of the following except:
– Defining Relationships Between Entities
– Identifying Entities
Defining Instances of Entities (*)
– Naming Relationships
2. Matrix Diagrams helps verify you have identified all possible relationships between your existing entities. True or False?
3. Creating a Matrix Diagram is mandatory when doing Data Modeling. True or False?