Week 2 -Chapter 3

Question 1

Used extensively in mathematics to provide a framework in which an assertion (statement of fact) can be verified as either true or false

Answer 1

Predicate Logic

Question 2

A part of mathematical science that deals with sets, or groups of things, and is used as the basis for data manipulation in the relational model

Answer 2

Set Theory

Question 3

In data modeling, the construct used to organize and describe and attirbutes set of possible values

Answer 3

Attribute Domain

Question 4

Also known as an attibute domain. It is the set of allowable values for an attribute.

Answer 4

Domain

Question 5

In the relational model, an identifier composed of one or more attributes that uniquely identifies a row, also a candidate key selected as a unique entity identifier

Answer 5

Primary Key PK

Question 6

One or more attributes that determine other attributes.

Answer 6

Key

Question 7

The role of a key. In the context of a database table, the statement “A determines B” inidicates that knowing the value of attribute A means that the value of attribute B can be looked up.

Answer 7

Determination

Question 8

Within a relation R, an attribute B is functionally dependent on an attribute A if and only if a given value of attibute A determines exactly one value of attribute B. The relationship “B is dependent on A” is equivalent to “A determines B” and is written as A -> B

Answer 8

Functional Dependence

Question 9

Any attribute in a specific row whose value directly determines other values in that row

Answer 9

determinant

Question 10

Any attribute whose value is determined by another attribute

Answer 10

Dependent

Question 11

A condition in which an attribute is functionally dependent on a composite key but not on any subset of the key

Answer 11

Full functional dependence

Question 12

A multiple attribute key

Answer 12

Composite key

Question 13

An attribute that is part of a primary key

Answer 13

Key attribute

Question 14

An attribute or attributes that uniquely identify each entity in a table

Answer 14

superkey

Question 15

A minimal superkey; that is, a key that does not contain a subset of attributes that is itself a superkey

Answer 15

candidate key

Question 16

The property of a relational table that guarantees each entity has a unique value in a primary key and that the key has no null values

Answer 16

Entity Integrity

Question 17

The absence of an attribute value. Note that a ____ is not a blank

Answer 17

Null

Question 18

A primary key from one table that is placed into another table to create a common attribute. The values in the __________ must be constrained to ensure referential integrity.

Answer 18

Foreign key FK

Question 19

A condition by which a dependent tables foreign key entry must have either a null entry or a matching entry in the primary key of the related table.

Answer 19

referential integrity

Question 20

A key used strictly for data retrieval purposes that does not require a functional dependency. For example, customers are not likely to know their customer number (PK), but the combination of last name, first name, mi, and telephone number will probably match the appropriate table row.

Answer 20

Secondary Key

Question 21

Special codes implemented by designers to trigger a required response, alert end users to specified conditions, or encode values. ____ may be used to prevent nulls by bringing attention to the absence of a value in a table.

Answer 21

Flags

Question 22

A set of mathematical principles that form the basis for manipulating relational table contents; the eight main functions are: SELECT, PROJECT, JOIN, INTERSECT, UNION, DIFFERENCE, PRODUCT, DIVIDE

Answer 22

RELATIONAL ALGREBRA

Question 23

Short for relation variable, a variable that holds a relation. A _____ is a container (variable) for holding relation data, not the relation itself.

Answer 23

RELVAR

Question 24

A property of relational operators that permits the use of relational algebra operators on existing tables (relations) to produce new relations

Answer 24

Closure

Question 25

A SQL command that yields the values of all rows or a subset of rows in a table. The ______ statement is used to retrieve data from tables. In relational algebra, ______ is an operator used to ____ a subset of rows. aka RESTRICT

Answer 25

SELECT

Question 26

In relational algebra an operator used to select a subset of columns.

Answer 26

PROJECT

Question 27

In relational algebra, an operator used to merge (append) two tables into a new table, dropping the duplicate rows. The tables must be union-compatible.

Answer 27

UNION

Question 28

Two or more tables that have the same number of colums and the corresponding columns have compatible domains.

Answer 28

Union-Compatible

Question 29

In relational algebra, an operator used to yield only the rows that are common to two union compatible tables.

Answer 29

INTERSECT

Question 30

In relational algebra, an operator used to yield all rows from one table that are not found in another union-compatible table.

Answer 30

DIFFERENCE

Question 31

In relational algebra, an operator used to yield all possible pairs of rows from two tables

Answer 31

PRODUCT

Question 32

In relational algebra, a type of operator used to yield rows from two tables based on criteria. There are many types of ____ natural, theta equi___, and outer

Answer 32

JOIN

Question 33

A relational operation that yields a new table composed of only the rows with common values in their common attributes.

Answer 33

natural join

Question 34

Columns that are used in the criteria of join operations. The ________ generally share similar values

Answer 34

join columns

Question 35

A join operator that links tables based on an equality condition that compares specified columns of the tables

Answer 35

equijoin

Question 36

A join operator that links tables using an inequality comparison operator (<. >, <=, >=) in the join condition.

Answer 36

theta join

Question 37

A join operation in which only rows that meet a given criterion are selected. The criterion can be an equality condition (natural join or equijoin) or an inequality condition (theta join). The most commonly used type of join.

Answer 37

Inner Join

Question 38

A join operation that produces a table in which all unmatched pairs are retained; unmatched values in the table are left null.

Answer 38

Outer Join

Question 39

A join operation that yields all the rows in the left table, including those that have no matching values in the other table.

Answer 39

left outer join

Question 40

A join operation that yields all of the rows in the right table, including the ones with no matching values in the other table.

Answer 40

right outer join

Question 41

In relational algebra, an operator that answers queries about one set of data being associated with all values of data in another set of data.

Answer 41

DIVIDE

Question 42

A detailed system data dictionary that describes all objects in a database

Answer 42

System Catalog

Question 43

The use of the same name to label different attributes. Should generally be avoided.

Answer 43

Homonyms

Question 44

The use of different names to identify the same object, such as an entity, an attribute, or a relationship; should generally be avoided

Answer 44

Synonyms.

Question 45

An entity designed to transform an M:N relationship into two 1:M relationships. The composite entity's primary key comprises at least the primary keys of the entities that it connects.

Answer 45

Composite entity, associative entity, bridge entity

Question 46

In the relational model, a table that implements an M:N relationship

Answer 46

Linking table

Question 47

An ordered array of index key values and row ID values (pointers). ______ are generally used to speed up and facilitate data retrieval

Answer 47

Index, Index Key

Question 48

An index in which the index key can have only one associated pointer value (row)

Answer 48

Unique index