Question

Question 1

[multiple answer] a relation in mathematics

1. Is much like a database table except that relations are sets, i.e. Don't allow duplicates whereas DBMSs may return tables with duplicates
2. Is not very much like a database table, because it only refers to such expressions as "greater than"
3. Is like a database table with exactly two columns, no more and no fewer
4. Is similar to a database table, but database tables cannot have infinitely many rows

Question 2

[multiple answers] in the relational model, relations are commonly used

1. To represent entities of the ER model
2. To represent relationships of the ER model
3. To represent multi-valued attributes
4. To represent derived attributes

Question 3

[multiple answers] constraints on relations in normal RDBMSs (not considering MS access)

1. Are tools for querying tables
2. Are tools for aiding data quality
3. Are tools for improving security
4. Are tools for filtering out records that should not get inserted

Question 4

[multiple answers] which of the following constraints can be violated by inserting a record into a database table?

1. Primary key constraint
2. Domain constraint
3. Referential integrity (foreign key) constraint
4. Constraint on null

Question 5

[multiple answers] which of the following constraints can be violated through a deletion of a record from a database table?

1. Primary key constraint
2. Domain constraint
3. Referential integrity (foreign key) constraint
4. Constraint on null

Question 6

[multiple answers] assume a table A with primary key aid, and a table B with primary key bid and foreign key aid which references aid in table A. Which of the following operations can result in a violation of the referential integrity (foreign key) constraint?

1. Insertion of a record into table A
2. Insertion of a record into table B
3. Deletion of a record from table A
4. Deletion of a record from table B

Question 7

[multiple answers] referentially triggered actions

1. May happen as a result of a deletion of a record because its primary key value is referenced by a foreign key value in a different relation
2. May happen as a result of a deletion of a record because it has a foreign key value that references a primary key value in a different relation
3. Are typically the result of defining a trigger for enforcing semantic integrity constraints
4. May happen as a result of an insertion of a record that defines a foreign key value for which no primary key value exists in a referenced table

Question 8

[multiple answers] a 1-to-1 relationship in the entity-relationship model can be represented in the relational model

1. By combining the two entities into one table
2. By adding a foreign key to one of the tables, which references the primary key of the other table
3. By creating a separate table that has two foreign keys, which reference the primary keys of the two tables that represent the entities
4. Cannot be represented at all in a relational database

Question 9

[multiple answers] a 1-to-many relationship in the entity-relationship model can be represented in the relational model

1. By combining the two entities into one table
2. By adding a foreign key to the table on the "many" side of the relationship, which references the primary key of the other table
3. By adding a foreign key to the table on the "1" side of the relationship that references the primary key of the other table
4. By creating a separate table that has two foreign keys, which reference the primary keys of the two tables that represent the entities

Question 10

[multiple answers] a many-to-many relationship in the entity-relationship model can be represented in the relational model

1. By combining the two entities into one table
2. By adding a foreign key to one of the tables, which references the primary key of the other table
3. By creating a separate table that has two foreign keys, which reference the primary keys of the two relations that represent the entities
4. Cannot be represented at all in a relational database

Answer 1

The answers to the questions are as follows:

QUESTION 1. a) Is much like a database table except that relations are sets, i.e. Don't allow duplicates whereas DBMSs may return tables with duplicates

QUESTION 2. b) in the relational model, relations are commonly used to represent entities of the ER model and the relationships of the ER model

QUESTION 3. b) and c)Are tools for filtering out records that should not get inserted

QUESTION 4. a) Primary key constraint and c) Referential integrity (foreign key) constraint

QUESTION 5. a) Primary key constraint and c) Referential integrity (foreign key) constraint

QUESTION 6. b) Insertion of a record into table B and c) Deletion of a record from table A

QUESTION 7. a) May happen as a result of a deletion of a record because its primary key value is referenced by a foreign key value in a different relation. and b) May happen as a result of a deletion of a record because it has a foreign key value that references a primary key value in a different relation.

QUESTION 8. b) By adding a foreign key to one of the tables, which references the primary key of the other table and c) by creating a separate table that has two foreign keys, which reference the primary keys of the two tables that represent the entities

QUESTION 9 b) by adding a foreign key to the table on the "many" side of the relationship, which references the primary key of the other table and d) By creating a separate table that has two foreign keys, which reference the primary keys of the two tables that represent the entities

QUESTION 10. c) By creating a separate table that has two foreign keys, which reference the primary keys of the two relations that represent the entities