The Relational Database Model

Helpfulness: 0
Set Details Share
created 4 years ago by Christine_Enderle
60 views
updated 4 years ago by Christine_Enderle
Grade levels:
College: Third year
show moreless
Page to share:
Embed this setcancel
COPY
code changes based on your size selection
Size:
X
Show:
1

Associative Entity

a entity designed to transform an many to many relationship in two one to many relationships (see composite entity)

2

Attribute Domain

in data modeling, the construct used to organize and describe an attribute's set of positive values (see domain)

3

Bridge Entity

The composite entity's primary key comprises at least the primary keys of the entities that it connects (see composite entity)

4

Candidate Key

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

5

Closure

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

6

Composite entity

a entity designed to transform an many to many relationship in two one to many relationships.The composite entity's primary key comprises at least the primary keys of the entities that it connects

7

Composite Key

a multiple-attribute key

8

Data Dictionary

stores the data definitions as well as their characteristics and relationships.

9

Dependent

an attribute whose value is determined by another attribute

10

Determinant

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

11

Determination

the role a key. i.e. knows the value of attribute A means that the value of attribute B can be looked up

12

Domain

in data modeling the construct used to organize and describe an attribute's set of possible values

13

Entity Integrity

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

14

equijion

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

15

flags

special codes implemented by designers to trigger a required response, alert end users to specified conditions, or encode values.

16

foreign key

an attribute or attributes in one table whose values must match the primary key in another table or whose values must be null

17

full functional dependence

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

18

functional dependence

within a relation R an attribute B is functionally dependent on an attribute A if and only if a given value of attribute A determines exactly one value of attribute B.

19

homonym

the use of the same name to label different attributes

20

index

an ordered array of index keys values and row ID values(pointers) indexes are generally used to speed up and facilitate data retrieval.

21

index key

indexes are generally used to speed up and facilitate data retrieval.(see index)

22

inner join

a join operation in which only rows that meet a given criterion are selected. Most commonly used join.

23

join columns

columns that join two tables. The join columns generally share similar values.

24

key

a entity identifier based on the concept of functional dependence ; keys may be classified in several ways.

25

key attribute

The attributes that form a primary key.

26

left outer join

in a pair of tables to be joined, a join that yields all the rows in the left table, including those that have no matching values in the other table

27

linking table

in the relational model a table that implements an many to many relationship

28

natural join

a relational operation that links tables by selecting only the rows and common values in their common attributes.

29

null

In sql, the absence of an attribute value. note that a null is not a blank.

30

outer join

a relational algebra JOIN operation that produces a table in which all unmatched pairs are retained.; unmatched values in the related tables are left null.

31

predicate logic

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

32

primary key

in relational model, an identifier composed of one or more attributes that uniquely identifies a row.

33

referential integrity

a condition by which a dependent table's foreign key must have either a null entry or a matching entry in the related table. Even though an attribute may not have a corresponding attribute.

34

relvar

short for relation variable, a variable that holds a relation. a relvar is a container (variable) for holding relation data,not the relation itself

35

right outer join

in a pair of tablesto be joined a join that yields all of the rows in the right table, including ones with no matching values in the other table.

36

secondary key

A key used strictly for data retrieval purposes. for example customers are not likely to know their customer numbers.

37

set theory

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

38

superkey

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

39

synonym

the use of a different word to identify the same object.

40

system catalog

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

41

theta join

a join operator that links tables using an inequality comparison operator. in the join condition.

42

tuple

in the relational model a table row.

43

union-compatible

Two or more tables that share the same column names and have columns with compatible data types or domains.

44

unique index

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