Lesson 6 Logical Database Design
For the database designer, which of the following is probably the most important information contained in the data dictionary?
Attributes for the relations in the database
Which of the following should be indentified and documented into the logical design phase?
Base relations of the database
Which of the following actions deletes any child keys associated with a parent key that has been deleted?
CASCADE
Ken is reviewing the conceptual data model of his travel database and discovers a relationship that has identifiable attributes. What should Ken do?
Create an entity to absorb the attributes
David has completed the conceptual models for a database that will track tsunami activity in the South Pacific. What is the next step David will take in designing his tsunami database?
Create logical data models
During the logical data model creation process, through which of the following are many-to-many relationships resolved?
Creation of intermediate entities
David is ready to validate the logical data model of his Tsunami tracking database. On which of the following documents will he rely heavily on to ensure that his database will support all user operations and system requirements?
Database requirements document
For which task would you use a database definition language (DBDL)?
Describe the structure of each relation
Consider the DBDL description of an entity shown in the exhibit: The highlighted portion of the description satisfies which integrity constraint?
Domain constraints
Which of the following integrity constraints defines the data type for an attribute?
Domain constraints
Consider the DBDL description of an entity shown in the exhibit: The highlighted portion of the description satisfies which integrity constraint?
Entity integrity
Which of the following integrity constraints ensures that all primary key attributes are not null?
Entity integrity
Ken has identified a many-to-many relationship in his travel database. The many-to-many relationship exists between the Passengers relation and the Flights relation. What should Ken do?
Ken should decompose the Passengers and Flights relations to create a new relation named Bookings
During which phase of the database design life cycle are relationships that may cause data manipulation anomalies identified and adjusted or removed?
Logical design phase
What is the cardinality of the relationship shown in the exhibit?
Many-to-many
The MySQL RESTRICT action is synonymous with which of the following actions?
NO ACTION
Which of the following actions prevents a parent key from being deleted if there are child keys that reference it?
NO ACTION
Which of the following actions allows deletions regardless of whether referential integrity is maintained?
NO CHECK
Consider the DBDL description of an entity shown in the exhibit: The highlighted portion of the description satisfies which integrity constraint?
Necessary data
Which of the following integrity constraints refers to any attributes that cannot be left blank or null under any circumstances?
Necessary data
Considering the information in the exhibit, which of the following can be said?
One passenger can take many flights and each flight can have many passengers
Ken is reviewing the conceptual data model of his travel database. In reviewing his Lodging table, he discovers an attribute that contains more than one value. What should Ken do?
Place the Lodging table into 1NF
What is the situation in which an entity is involved in a relationship with itself known as?
Recursive relationship
Consider the DBDL description of an entity shown in the exhibit: The highlighted portion of the description satisfies which integrity constraint?
Referential integrity
Which of the following integrity constraints ensures that all foreign keys associate an existing parent key in a parent relation?
Referential integrity
Consider the DBDL description of an entity shown in the exhibit: What will happen if a record for a customer is deleted from the Customers relation and there are several records in the orders relation which reference that customer?
The record in the Customer relation cannot be deleted if there records in the Orders relation reference it.
Consider the DBDL description of an entity shown in the exhibit: What will happen if a record for a customer is deleted from the Customers relation and there are several records in the Orders relation which reference that customer?
The referencing records in the Orders relation will also be deleted
Which of the following is true about many-to-many relationships?
They must be eliminated in the relational data model
Using the ER diagram of the logical data model he has created for Travel database, Ken manually writes each required transaction to ensure that all the data required to carry out the transaction is present. Ken has also made arrangements to meet with several users of the database system in order to review the ER diagram. What is Ken doing?
Validating the logical data model
