Chapter 3 Quiz Flashcards
Which of the following is not a valid characteristic of a relational table?
a. It is perceived as a two-dimensional structure composed of rows and columns.
b. The order of the rows and columns is irrelevant to the DBMS.
c. Each table column represents an attribute and each column has a distinct name.
d. All values in a column may have different data formats.
d
The proper use of foreign keys _____ data redundancies and the chances that destructive data anomalies will develop.
minimizes
A composite entity is also referred to as a _____ entity.
bridge
Which of the following is not a legitimate DB key in a relational model?
a. Superkey
b. Entity key
c. Secondary key
d. Candidate key
b
Dr. Codd published a list of 12 relational database rules in 1985; which of the following is not a valid rule?
a. Any database view that is theoretically updatable must be updated outside of the database structure.
b. The database must support set-level inserts, updates, and deletes.
c. Every value in a table is guaranteed to be accessible through a combination of table name, primary key value, and column name.
d. Nulls must be represented and treated in a systematic way, independent of data type.
a
Which of the following statements best defines the purpose of entity integrity?
a. It secures the null key in the absence of any data.
b. It guarantees each entity has a unique value for the primary key and that there are no null key values.
c. It validates each row will have a value identifying foreign key values in other tables.
d. Lacking a primary key, it enables each row to identify other rows in other tables.
b
Which of the following statements best describes a functional dependency?
a. The condition in which each row in the table is dependent on any subset of the key.
b. The value of an attribute determines the value of one or more other attributes.
c. The value of one or more attributes determines the value of one or more other attributes.
d. The data type of an attribute determines the data type of another attribute.
c
Which of the following best describes an index?
a. It is a variable for holding database relation data, not the relation itself.
b. An index is an orderly arrangement used to logically access rows in a table.
c. It has an attribute with a value that determines the value of other rows.
d. An index is an orderly arrangement used to physically access rows in a table.
b
Which of the following statements best defines a data dictionary?
a. The data dictionary provides a detailed description of all entities in the database created by the user and designer.
b. The data dictionary provides a detailed description of all tables in the database created by the developer and designer.
c. The data dictionary provides a detailed description of all entities in the database created by the developer and designer.
d. The data dictionary provides a detailed description of all tables in the database created by the user and designer.
d
Which of the following is not a valid relational set operator?
a. INTERSECT operator
b. UNION operator
c. ADD operator
d. DIFFERENCE operator
c
