WGU C175 Study Notecards

Flat Files - answer-a file having no internal hierarchy Hashed Files - answer-A file that has been encrypted for security purposes. Heap File - answer-An unsorted set of records. Information - answer-The transformation of raw data into useful facts. Punch Card - answer-A card that is perforated and can hold commands or data. Structured Data - answer-Information with a high degree of organization. Unstructured Data - answer-Information that does not have structure (such as text) Binary Relationship - answer-A relationship between two entity types. Unary Relationship - answer-An associate occurrence of an entity type with other occurrences of the same entity type. Cardinality - answer-The maximum number of entities that can be involved in a particular relationship. E-R Model *E-R = Entity - Relationship - answer-Diagram of entities together with their attributes and the relationship among them. Intersection Data - answer-It is data that describes a many-to-many relationship. Modality - answer-It is a minimum number of entity occurrences that can be involved in a relationship. One-to-one Binary Relationship - answer-It means that a single occurrence of one entity type can be associated with a single occurrence of the other entity type and vice versa. Ternary Relationship - answer-Involves three different entity types. Unique identifier - answer-It is used to uniquely identify each record in a database table. Attribute - answer-A property, characteristic, or fact that we know about an entity. "A salesperson works in one office." What is the name of this relationship? - answer-One-to-one binary relationship "A salesperson sells to many customers." What is the name of this relationship? - answer-One-to-many binary relationship "A salesperson is authorized to sell many products, and a product can be sold by many salespersons." What is the name of this relationship? - answer-Many-to-many binary relationship What is the positioning and meaning for Cardinality and Modality on an E-R model? - answer-Cardinality is the outer symbol; represents the maximum. Modality is the inner symbol; represents the minimum. "A salesperson works in a minimum of one and a maximum of one office, and an office may be occupied by or assigned to a minimum of zero and a maximum of one salesperson." - answer- "A salesperson may have no customers or many customers." - answer- Describe the ER model for "Each salesperson is authorized to sell to at least one or many products, and each product can be sold by at least one or many salespeople." - answer- "One salesperson backs-up another salesperson." What is the name of this model? - answer-One-to-one unary relationship "A salesperson manages zero to many other salespersons, and a salesperson is managed by exactly one other salesperson." What is the name of this model? - answer-One-to-many unary relationship "A product can either be part of no other products or be part of several other products, and a product can either be composed of no other products or be composed of several other products." What is the name of this model? - answer-Many-to-many unary relationship What does 'refer' in Referential Integrity imply? - answer-This revolves around the circumstance of trying to refer to data in one relation in the database, based on values in another relation. Define the delete rule RESTRICT. - answer-If the delete rule between two relations is RESTRICT and an attempt is made to delete a record on the "one side" of the one-to-many relationship, the system will forbid the delete to take place if there are any matching foreign key values in the relation on the "many side". Define the delete rule CASCADE. - answer-If the delete rule between two relations is CASCADE and an attempt is made to delete a record on the "one side" of the relationship, not only will the record be deleted but all of the records on the "many side" of the relationship that have a matching foreign key value will also be deleted. In other words, the delete will "cascade" from one relation to the other. Define the delete rule SET-TO-NULL. - answer-If the delete rule between the two relations is SET-TO-NULL and an attempt is made to delete a record on the "one side" of the one-to-many relationship, that record will be deleted and the matching foreign key values in the records on the "many side" of the relationship will be set to null. Essentially, it's exactly like the CASCADE delete option, but instead of completely deleting all possible values, the values are set to NULL instead. Which entity is uniquely identified by concatenating the primary keys of the two entities it connects? - answer-Associative Entity