Mid-Term Questions Flashcards
The only serious problem with file-processing systems instead of relational databases is the amount of wasted storage space on disk. (T/F)
F
If one database table (say, registration record) contains a student’s last name and address and another table (say, dorm allocation record) also contains a student’s last name and address, we have the potential for data integrity problems (i.e., we run into the possibility of having insert, update and delete and delete anomalies).
(T/F)
T
If one database table (say, registration record) contains a student’s last name and address and another table (say, dorm allocation record) also contains a student’s last name and address, we have the potential for data integrity problems (i.e., we run into the possibility of having insert, update and delete and delete anomalies).
Data integrity as described above is an issue with database systems only - if we had used a file processing system instead, we would never have this problem. (T/F)
F
[Delete] anomalies are caused when you can’t put a new row in a table unless you have some totally “irrelevant” data available (e.g., you cannot put an individual’s data into a “Borrower” table unless you know his/her current blood pressure). (T/F)
F
According to the relational database model, undesirable table can be changed into two or more desirable tables through a process called ‘modularization’. (T/F)
F
A key benefit of the relational database model was that it provided a standardized (e.g., non file-format dependant) way for specialists to structure and process a database system. (T/F)
T
In a relation, the columns of the relation fields or attributes, and the rows of the relation contain records for particular entities in the business environment. (T/F)
T
A single database table could have multiple candidate keys. (T/F)
T
A “first-class entity” in a UML-style E-R diagram (i.e., a “box” that [does not] represent a relationship between two other entities) always maps on to a database table in the final schema for the database. (T/F)
T
In an E-R diagram, a “box” showing a relationship [with attributes] always maps on to a database table in the final schema for the database. (T/F)
T
Relationships are always of one-many cardinality. (T/F)
F
A table is in First Normal Form id also always in Second Normal Form.
F
The concept of inheritance is ell suited to the nature of a relational data model as well as that of an object-oriented data model. (T/F)
F
In a relation, Attribute Y is [functionally dependent] on attribute X if the value of attribute X determines the value of Y. (T/F)
T
In the functional dependency shown as A -> B, B is the determinant. (T/F)
F
A transaction processing system must [not]:
i. Be highly available
ii. Have a good response time
iii. Have low “down time”
iv. Be reliable
v. Be geographically limited
v. Be geographically limited
Which of the following is known to be true from the functional dependency shown as (A,B) -> (C,D)?
i. A is the determinant of C
ii. A and B together are determine by C and D together
iii. A and B together determine D
iv. C and D together determine A
v. A determine B
iii. A and B together determine D
Which of the following is known to be true from the functional dependency shown as A -> (X, Y)?
i. A determines X
ii. A determines Y
iii. A is a determinant
iv. X and Y are functionally dependent on A
v. All of the above
v. All of the above
Which of the following is NOT a requirement for 1NF?
i. Cells must contain single values
ii. All entries in a column must be of the same kind
iii. Not two rows may be identical
iv. Rows must be ordered by the value of the key
v. The order of the columns is significant
iv. Rows must be ordered by the value of the key
A relation is in 2NF if it is in 1NF and all its non-key attributes are:
i. Dependant on part of the key
ii. Dependant on [all] of the key
iii. Independent of the key
iv. Independent of each other
v. Independent of any other relation
ii. Dependant on [all] of the key
Which if the following is a requirement is a requirement of 3NF?
i. Must contain a partial dependency
ii. Must contain a composite key
iii. Must contain no partial dependencies
iv. Must contain no transitive dependencies
v. Must contain a multi-valued dependency
iv. Must contain no transitive dependencies
A “candidate key” is:
i. A primary key.
ii. Any group of attributes that are a determinant.
iii. Functionally dependent on the non-key attributes.
iv. An attribute or a group of attributes that can be the key.
v. The primary key selected to be the key of a relation.
iv. An attribute or a group of attributes that can be the key.
A relation is in Boyce-Codd normal form if it is in 3NF and:
i. Every determinant is a full candidate key.
ii. Every determinant is the full one and only primary key.
iii. Every attribute is a candidate key.
iv. There is more than one candidate key.
v. There is more than on primary key.
i. Every determinant is a full candidate key.
A relation is in fourth normal form if it is in BCNF and it has no:
i. Transitive dependencies
ii. Multi-valued dependencies
iii. Partial dependencies
iv. Deletion dependencies
v. Referential integrity conflicts
ii. Multi-valued dependencies
