ISQS 3348 Chapter 2 quiz

Given the functional dependency for the attributes of ENTITY1, X → (A, B, C), X is a candidate key for the relation ENTITY1 (A, B, C, X).

Answer: TRUE

If the condition exists such that knowing the value of attribute X determines the value attribute Y, then attribute Y is functionally dependent on attribute X.

Answer: TRUE

Null values can cause problems because they are ambiguous.

Answer: TRUE

Which of the following is true about a relation? A) The order of the columns in a relation must go from largest to smallest. B) All entries in any column must be of the same kind. C) A relation may have duplicate column names. D) A relation may have duplicate rows. E) A relation may have multiple names.

B) All entries in any column must be of the same kind.

) A table that meets the requirements of a relation is said to be in which normal form? A) Relational normal form (RNF) B) First normal form C) Second normal form D) Boyce-Codd normal form E) Domain/key normal form

B) First normal form

Which of the following is true about a key? A) It may be unique. B) It may be non-unique. C) In may identify more than one row. D) Both A and B E) All of the above

B) It may be non-unique

Which of the following is not true about a relation? A) A relation is a two-dimensional table. B) The cells of a relation must hold a single value. C) A relation may have duplicate column names. D) A relation may not have duplicate rows. E) The order of the rows of a relation is insignificant.

C) A relation may have duplicate column names.

STUDENT (SID, StudentName, Major, AdvisorID) ADVISOR (AdvisorID, AdvisorName, Office, Phone) Given the relations above such that each student is assigned to one advisor, which of the following is true? A) SID is both a primary key and a foreign key. B) AdvisorName is a determinant. C) AdvisorID is a foreign key. D) Phone is a candidate key. E) Major is a candidate key.

C) AdvisorID is a foreign key

During the normalization process, the remedy for a relation that is not well formed is to: A) create a surrogate key. B) create a functional dependency. C) break it into two or more relations that are well formed. D) combine it with another relation that is well formed. E) convert it into a list.

C) break it into two or more relations that are well formed

In Microsoft Access, a relationship between two tables is created: A) by entering the name of the foreign key in the appropriate table in Design View. B) by entering the name of the primary key in the appropriate table in Design View. C) by dragging the primary key column of one table onto the foreign key column of the other table in the Relationships window. D) by dragging the foreign key column of one table onto the primary key column of the other table in the Relationships window. E) by dragging the primary key column of one table onto the primary key column of the other table in the Relationships window.

C) by dragging the primary key column of one table onto the foreign key column of the other table in the Relationships window.

When the primary key of one relation is placed into a second relation, it is called a: A) field key. B) referential integrity. C) foreign key. D) candidate key. E) relocated key

C) foreign key.

In Microsoft Access, relationships between tables are created: A) by the Relationships button on the Create command tab. B) by the Relationships button on the Home command tab. C) in the Relationships window. D) in the Table window of the table containing the primary key. E) in the Table window of the table containing the foreign key.

C) in the Relationships window.

When the primary key of one relation is placed in a second relation to represent a relationship, the attribute in the second relation is called a(n) ________ key.

foreign

The relationship between two attributes that denotes that if the value of the first attribute is known, then the value of the second attribute can be determined, is called a(n) ________.

functional dependency

A(n) ________ is one or more columns of a relation that is used to identify a row

key

Although Microsoft Access is a personal database, the database tables in Access are still subject to ________ if they are not well-formed.

modification problems

The key that has been designated the ________ key of a relation functionally determines all the other attributes in the relation.

primary

To create a relationship in Microsoft Access, we drag and drop the ________ of a table.

primary key

A rule that requires every value in a foreign key to match values in the corresponding primary key is called a(n) ________ constraint.

referential integrity

Any table that meets the requirements of a(n) ________ is in first normal form.

relation

What requirements must a two-dimensional table satisfy in order to be a relation?

For a table to be considered a relation, it must meet several requirements. First, every cell must contain a single value. Second, there can be no duplicate rows. Third, each column must have a unique name. Fourth, the order of the columns must have no significance. Fifth, all values for a given column must be of the same type. Finally, the order of the rows must have no significance.

In practice, why would tables that have duplicate rows be allowed?

It is not uncommon for a table that is returned as the result of a data manipulation operation, such as a query, to contain duplicate rows. This is often tolerated because of the processing time necessary for the DBMS to search the table to find and eliminate duplicate rows. This is especially true if the table is very large. In these cases, it is often acceptable to allow the duplicate rows to exist.

What is normalization?

Normalization is a process whereby relations that are not well-formed are modified to become well-formed relations. A relation is considered to be well-formed if the data within it are not subject to unintended negative consequences when it is maintained. Although normalization recognizes several different normal forms, which are categories that the structure of a relation can be classified into based on the types of problems to which it is vulnerable, the basic premises of normalization are that (1) every determinant should be a candidate key, and (2) any relation that is not well formed should be broken into two or more relations that are well-formed.

In Microsoft Access, the Relationships window is accessed by using the ________ button on the Database tools command tab.

Relationship

In Microsoft Access, relationships between tables are built in the ________.

Relationships window.

Every cell in a relation can hold only a single value

TRUE

Every relation is a table, but not every table is a relation.

TRUE

In Microsoft Access, relationships between tables are created in the Relationships window.

TRUE

In the normalization process, if you find that every determinant in a relation is a candidate key, then you have determined that the relation is well formed.

TRUE

In the normalization process, it is necessary to identify all the determinants in a relation.

TRUE

Surrogate key values have no meaning to the users.

TRUE

The first step of the normalization process is to identify all the candidate keys of a relation.

TRUE

The primary key is used both to identify unique rows in a relation and to represent rows in relationships.

TRUE

To be considered a composite key, a key must contain at least two attributes.

TRUE

To create a well-formed relation through normalization, every determinant must be a candidate key.

TRUE

To represent a relationship in the relational model, the primary key of one relation is placed into a second relation.

TRUE

To be a well-formed relation, every ________ in the relation must be a candidate key

determinant

Explain the concept of a functional dependency

A functional dependency is a relationship that exists among the attributes of a relation, such that if the value of one attribute or group of attributes is known, the value of another attribute or group of attributes can be determined. In a functional dependency, the attribute(s) whose value determines the value of the other attribute is called the "determinant." The other attribute, whose value is determined by the determinant, is said to be functionally dependent on the determinant.

Explain the concept of a surrogate key.

A surrogate key is an artificial key that is created to act as the primary key for a relation. The surrogate key is a unique, numeric value that is appended to the relation. Surrogate keys are used in situations when no suitable primary key exists within the user data, or when all available primary keys within the data are too cumbersome for an efficient design. Surrogate key values have no meaning to the users and are normally hidden on all forms, reports, and displays. Most DBMS products have the ability to automatically generate values for surrogate keys as needed.

Which of the following is not true of surrogate keys? A) They are meaningful to the users. B) They are numeric. C) They are usually generated by the DBMS. D) They are unique. E) They are usually hidden on forms and reports.

A) They are meaningful to the users.

A key that contains more than one attribute is called a(n): A) composite key. B) complex key. C) multi-key. D) n-key. E) candidate key

A) composite key.

One important relational design principle is that: A) every determinant must be a candidate key. B) every candidate key must not be a determinant. C) every primary key must be a surrogate key. D) every determinant must be functionally dependent on the primary key. E) every primary key must be functionally dependent on every determinant.

A) every determinant must be a candidate key.

The first step of the normalization process is to: A) identify all the candidate keys of a relation. B) identify all the foreign keys of a relation. C) identify all the functional dependencies of a relation. D) identify all the determinants of a relation. E) split the relation into two or more new relations.

A) identify all the candidate keys of a relation.

In the normalization process, if you find that every determinant in a relation is a candidate key then you have determined that: A) the relation is well formed. B) the relation needs to be broken into two or more new relations. C) surrogate keys in the relation may not be correctly linked to other relations. D) the relation needs to have foreign keys added in order to be correctly linked to other relations. E) referential integrity constraints concerning the relation need to be established.

A) the relation is well formed.

MedicineCode → (MedicineName, ShelfLife, Manufacturer, Dosage) Given the above functional dependency, which of the following statement is not known to be true? A) MedicineCode is a determinant. B) MedicineName is a determinant. C) Manufacturer is functionally dependent on MedicineCode. D) ShelfLife is functionally dependent on MedicineCode. E) MedicineCode is a candidate key of the relation MEDICINE (MedicineName, ShelfLife, Manufacturer, Dosage, MedicineCode).

B) MedicineName is a determinant.

Which of the following terms is synonymous with "relation"? A) Attribute B) Table C) Record D) Row E) Tuple

B) Table

A rule that requires that the values in a foreign key must have a matching value in the primary key to which the foreign key corresponds is called: A) normalization. B) a referential integrity constraint. C) a key matching constraint. D) a functional dependency. E) synchronization.

B) a referential integrity constraint

In the normalization process, it is not necessary to: A) identify all the candidate keys of a relation. B) identify all the foreign keys of a relation. C) identify all the functional dependencies of a relation. D) identify all the determinants of a relation. E) determine if every determinant is a candidate key.

B) identify all the foreign keys of a relation.

What are the basic steps of the normalization process?

Before starting the normalization process, the relation must be in first normal form, which means that it meets the basic requirements of being a relation. The first step of the normalization process is to identify all the candidate keys in the relation. The second step is to identify all the functional dependencies in the relation. Third, check to see if all the identified determinants are candidate keys. If all determinants are candidate keys, the relation is well-formed and nothing more needs to be done. On the other hand, if any of the determinants is not a candidate key, the relation is not well-formed, and it is necessary to: (1) place the columns of that functional dependency into a new relation, (2) make the determinant of that functional dependency the primary key of the new relation, (3) leave a copy of the determinant in the original relation as a foreign key, and (4) create a referential integrity constraint between the original relation and the new relation. This process should be repeated for every relation until every determinant in a relation is a candidate key of that relation.

Distinguish between the primary key and a candidate key.

Both the primary key and a candidate key can uniquely identify the rows in a table. The primary key is the candidate key that is chosen by the database designer, working with the users, to uniquely identify rows and to represent relationships. Although any candidate key could, by definition, be selected to act as the primary key, the choice of primary key is often based on design decisions such as the amount of foreign key data that would be generated.

) In the normalization process, if you find a candidate key that is not a determinant then you should: A) place the columns of the functional dependency in a new relation. B) make the determinant of the functional dependency the primary key of the new relation. C) leave a copy of the determinant as a foreign key in the original relation. D) All of the above E) None of the above

D) All of the above

Although Microsoft Access is a personal database, it is still subject to the following modification problem(s): A) problems adding data. B) problems changing data. C) problems deleting data. D) All of the above E) None of the above

D) All of the above

In SQL Server, the starting value of a surrogate key is called the: A) Identity. B) Identity Increment. C) Identity Start. D) Identity Seed. E) Identity Property.

D) Identity Seed

Which of the following terms is synonymous with "tuple"? A) Attribute B) Table C) Field D) Row E) Relation

D) Row

In Microsoft Access, the relationship between two tables is not actually created until: A) the OK button in the Create Relationships dialog box is clicked. B) the Create button in the Create Relationships dialog box is clicked. C) the OK button in the Edit Relationships dialog box is clicked. D) the Create button in the Edit Relationships dialog box is clicked. E) the Join button in the Edit Relationships dialog box is clicked.

D) the Create button in the Edit Relationships dialog box is clicked.

) Which of the following functional dependency diagrams accurately represents the following situation: • A campus has many buildings. • Each building has a unique name. • Each building has many rooms. • All rooms in any given building are numbered sequentially starting at "101." • Each room has a certain capacity, although many rooms in the same building or different buildings may have the same capacity. • Each room is assigned to a single department. • A department may have many rooms in one or more buildings, each with the same or different capacities. A) BuildingName → (RoomNumber, Capacity, Department) B) RoomNumber → (BuildingName, Department, Capacity) C) (Department, Capacity) → (BuildingName, RoomNumber) D) (BuildingName, Capacity) → (Department, RoomNumber) E) (BuildingName, RoomNumber) → (Capacity, Department)

E) (BuildingName, RoomNumber) → (Capacity, Department)

A primary key is: A) required to be unique. B) used to represent rows in relationships. C) a candidate key. D) used to identify unique rows. E) All of the above

E) All of the above

A candidate key is: A) required to be unique. B) used to represent rows in relationships. C) a candidate to be the primary key. D) Both A and B E) Both A and C

E) Both A and C

A surrogate key may be appropriate under which of the following circumstances? A) The available candidate keys would produce a lot of data duplication when representing relationships. B) The primary key is numeric. C) The available candidate keys would be prone to typographical errors. D) The available candidate keys have little meaning to the users. E) Both A and C

E) Both A and C

In the normalization process, if you find a candidate key that is not a primary key then you should: A) place the columns of the functional dependency in a new relation. B) make the determinant of the functional dependency the primary key of the new relation. C) leave a copy of the determinant as a foreign key in the original relation. D) All of the above E) None of the above

E) None of the above

Which of the following is not true about null values? A) A null value can mean that the value is unknown. B) A null value is ambiguous. C) A null value can mean that the value is known to be blank. D) A null value can mean that no value for the field is appropriate. E) Null values cannot be avoided

E) Null values cannot be avoided

Briefly describe the various tasks of the primary key.

The primary key is used for four primary tasks. First, it is used to uniquely identify the rows in a table. Second, it is used to represent rows in relationships. Third, most DBMS products use the values of the primary key to organize the storage of the relation. Finally, primary keys are used in indexes and other structures to improve performance for search operations.

) In Microsoft Access, referential integrity constraints are created: A) by setting a property value on the primary key in the table which contains it. B) by setting a property value on the foreign key in the table which contains it. C) by setting a property value on the primary key in the Relationships window. D) by setting a property value on the foreign key in the Relationships window. E) by checking the Enforce Referential Integrity check box in the Edit Relationships dialog box.

E) by checking the Enforce Referential Integrity check box in the Edit Relationships dialog box.

In Microsoft Access, referential integrity constraints are created in the ________.

Edit Relationships dialog box.

A key must be unique.

FALSE

Any table that meets the definition of a relation is said to be in second normal form.

FALSE

Candidate keys may or may not be unique

FALSE

Every table is a relation, but not every relation is a table

FALSE

In Microsoft Access, a relationship is created by dragging a foreign key column and dropping it on top of the corresponding primary key.

FALSE

In Microsoft Access, foreign keys are designated by using the Foreign Key button in the toolbar.

FALSE

In the normalization process, if you find a candidate key that is not a primary key, then you have determined that the relation needs to be broken into two or more other relations.

FALSE

In the normalization process, it is not necessary to identify all the functional dependencies in a relation

FALSE

In the relational model, each row of a table contains data that represents an attribute of the entity.

FALSE

Microsoft Access forms can only contain data from one table.

FALSE

Normalization is the process of removing all functional dependencies from a relation.

FALSE

Since Microsoft Access is a personal database, it is not subject to the modification problems that occur in other relational databases.

FALSE

Since surrogate keys are used to uniquely identify rows, their values are normally displayed prominently on all forms and reports for the users to see.

FALSE

The use of surrogate keys usually complicates application programming since most DBMS products require the application program to generate surrogate key values.

FALSE

When used to represent a relationship, the primary key must have the same name as the corresponding foreign key.

FALSE

While the relational model for databases appears to hold much promise, few commercial databases have implemented it.

FALSE

Explain the possible interpretations of a null value.

The problem with allowing null values in a table is that the null value is open to three different interpretations. First, a null value in a field may mean that no value is appropriate for the field for the given record. Second, a null value may mean that the value of that field is known to be blank for the given record. Third, a null value may mean that the value of that field is not known for the given record.

Explain the terms relation, tuple, and attribute

The terms relation, tuple, and attribute are used primarily by database theoreticians. These terms are synonymous with the terms table, row, and column, respectively, in regards to a relational database. They are also equivalent to the terms file, record, and field, which tend to be used by many traditional data processing professionals.

Explain the concept of a foreign key

To implement a relationship within a relational database, the primary key of one relation is placed as an attribute in another relation. This attribute is called a foreign key in the second relation because it is the primary key of a relation that is foreign to the table in which the field resides.

The unique keys that are not chosen to be the primary key are called ________ keys.

candidate

A key that contains two or more attributes is called a(n) ________ key.

composite

A(n) ________ is a unique, numeric value that is appended to the relation to serve as the primary key

surrogate key