Database Design Flashcards
Entities, relationships, and attributes. Cardinality. Strong and weak entities. Supertype and Subtypes. Modeling Conventions. (118 cards)
1
Q
Entity-Relationship Model
A
High-level representation of data requirements, ignoring implementation details
2
Q
Entity
A
Person, place, product, concept or activity
3
Q
Relationship
A
Statement about two entities
4
Q
Attribute
A
Descriptive property of an entity
5
Q
Reflexive relationship
A
Relates to an entity itself
6
Q
entity-relationship diagram, ER Diagram
A
schematic picture of entities, relationships, and attributes
7
Q
Glossary/Data Dictionary/Repository
A
Documents additional detail in text format
8
Q
Entity Type
A
a set of things Ex: All employees in a company.
9
Q
Relationship Type
A
Is a set of related things (Employee-Manages-Department is a set of (employee, department) pairs, where the employee manages the department
10
Q
Attribute Type
A
Set of values Ex: All employee salaries
11
Q
Entity Instance
A
individual thing Ex: The employee Sam Snead
12
Q
Relationship Instance
A
Statement about an entity instance Ex: “Maria Rodriguez manages Sales”
13
Q
Attribute Instance
A
An individual value Ex: The Salary $35,000
14
Q
Analysis
A
Develops an entity-relationship model, capturing data requirements while ignoring implementation details
15
Q
Logical Design
A
Converts the entity-relationship model into tables, columns, and keys for a particular database system.
16
Q
Physical design
A
Adds indexes and specifies how tables are organized on storage media
17
Q
Cardinality
A
Refers to the maxima and minima of relationships and attributes
18
Q
Relationship Maximum
A
Greatest number of instances of one entity that can relate to a single instance of another entity
19
Q
Singular/Plural
A
Single when the maximum is one and plural when the maximum is many
20
Q
Relationship Minimum
A
Least number of instances of one entity that can relate to a single instance of another entity
21
Q
Optional/REquired
A
Optional when the minimum is zero and required when the minimum is one.
22
Q
Attribute Maximum
A
Greatest number of attribute values that can describe each entity instance. Attribute maximum is usually specified as one singular or many plural
23
Q
Attribute Minimum
A
last number of attribute values that can describe each entity instance. Attribute minimum is usually specified as zero or one required.
24
Q
Unique Attribute
A
Describes at most one entity instance
25
Identifying attribute
unique, singular, and required
26
Identify
Values correspond to one-to-one to, or identify, entity instances.
27
strong entity
Has one or more identifying atytributes
28
Weak Entity/Identifying Relationship/Identifying entity
Weak entity usually has a relationship, called an identifying relationship, to another entity, called an identifying entity. Cardinality of the ID entity is 1(1)
29
Subtype Entity/Supertype Entity
Subtype entity is a subset of another entity type, called the supertype entity
30
IsA Relationship
A Super type entity identifies its subtype entities. The identifying relationship is called an IsA relationship
31
Similar Entities
Entities that have many common attributes and relationships
32
Partition
Supertype entity is a group of mutually exclusive subtype entities
33
Partition Attribute
Corresponds to an optional partition attribute of the super type entity
34
Crow's Foot Notation
Depicts cardinality as a Circle(zero), a short line (one) or three short lines(many)
35
Subject Area
Decompose a complex model into a group of related entities, called a subject area
36
Independent/Dependent
Refers to strong entities as independent and weak entities as dependent
37
Unified Modeling Language/UML
Commonly used for software development. Software data structures are similar to database scructures, so UML includes ER conventions
38
IDEF1X
Information DEFinition Version 1x
39
Chen Notation
Chen notation is not standardized but often appears in literature and tools
40
Strong Table
Strong Entity becomes a strong table. Primary key must be unique and non-NULL, and should be stable, simple, and meaningless. Single-column primary keys are best. but if no such columns exists, a composite primary key may have the required properties.
41
Artificial Key
Single-Column primary key created by the database designer when no suitable single-column or composite primary key exists
42
Subtype Table
Subtype entity becomes a subtype table
43
Weak Table
Weak entity becomes a weak table
44
Depends on
Column A depends on Column B means each B value is related to at most one A value
45
Functional Dependence
Dependence of one column on another
46
Multivalued dependence/Join Dependence
Entail dependencies between three or more columns
47
Redundancy
Reptition of related values in a table
48
Normal forms
Rules for designing tables with less redundancy
49
First normal form
Every cell of a table contains exactly one value. The table has a primary key as well.
50
Second Normal Form
When all non-key columns depend on the whole primary key
51
Third Normal Form
When all non-key columns depend on the key, the whole key, and nothing but the key.
52
Candidate Key/Minimal
Simple or composite column that is unique and minimal. Minimal means all columns are necessary for uniqueness
53
Nonkey
Column that is not contained in a candidate key
54
Third normal form
Whenever a non-key column A depends on column B, then B is unique. Columns A and B may be simple or composite
55
Boyce-Codd Normal Form
Whenever column A depends on Column b, then B is unique. Columns A and B may be simple or composite
56
Normalization
Eliminates redundancy by decomposing a table into two or mote tables in higher normal form.
57
Depends On
Column A depends on column when each b value is related to at most one A value. A and B may be simple or composite columns
58
Boyce-Codd Normal Form
If Column A depends on column B, then B must be unique
59
Denormalization
Intentionally introducing redundancy by merging tables
60
High-level representation of data requirements, ignoring implementation details
Entity-Relationship Model
61
Person, place, product, concept or activity
Entity
62
Statement about two entities
Relationship
63
Descriptive property of an entity
Attribute
64
Relates to an entity itself
Reflexive relationship
65
schematic picture of entities, relationships, and attributes
entity-relationship diagram, ER Diagram
66
Documents additional detail in text format
Glossary/Data Dictionary/Repository
67
a set of things Ex: All employees in a company.
Entity Type
68
Is a set of related things (Employee-Manages-Department is a set of (employee, department) pairs, where the employee manages the department
Relationship Type
69
Set of values Ex: All employee salaries
Attribute Type
70
individual thing Ex: The employee Sam Snead
Entity Instance
71
Statement about an entity instance Ex: "Maria Rodriguez manages Sales"
Relationship Instance
72
An individual value Ex: The Salary $35,000
Attribute Instance
73
Develops an entity-relationship model, capturing data requirements while ignoring implementation details
Analysis
74
Converts the entity-relationship model into tables, columns, and keys for a particular database system.
Logical Design
75
Adds indexes and specifies how tables are organized on storage media
Physical design
76
Refers to the maxima and minima of relationships and attributes
Cardinality
77
Greatest number of instances of one entity that can relate to a single instance of another entity
Relationship Maximum
78
Single when the maximum is one and plural when the maximum is many
Singular/Plural
79
Least number of instances of one entity that can relate to a single instance of another entity
Relationship Minimum
80
Optional when the minimum is zero and required when the minimum is one.
Optional/REquired
81
Greatest number of attribute values that can describe each entity instance. Attribute maximum is usually specified as one singular or many plural
Attribute Maximum
82
last number of attribute values that can describe each entity instance. Attribute minimum is usually specified as zero or one required.
Attribute Minimum
83
Describes at most one entity instance
Unique Attribute
84
unique, singular, and required
Identifying attribute
85
Values correspond to one-to-one to, or identify, entity instances.
Identify
86
Has one or more identifying atytributes
strong entity
87
Weak entity usually has a relationship, called an identifying relationship, to another entity, called an identifying entity. Cardinality of the ID entity is 1(1)
Weak Entity/Identifying Relationship/Identifying entity
88
Subtype entity is a subset of another entity type, called the supertype entity
Subtype Entity/Supertype Entity
89
A Super type entity identifies its subtype entities. The identifying relationship is called an IsA relationship
IsA Relationship
90
Entities that have many common attributes and relationships
Similar Entities
91
Supertype entity is a group of mutually exclusive subtype entities
Partition
92
Corresponds to an optional partition attribute of the super type entity
Partition Attribute
93
Depicts cardinality as a Circle(zero), a short line (one) or three short lines(many)
Crow's Foot Notation
94
Decompose a complex model into a group of related entities, called a subject area
Subject Area
95
Refers to strong entities as independent and weak entities as dependent
Independent/Dependent
96
Commonly used for software development. Software data structures are similar to database scructures, so UML includes ER conventions
Unified Modeling Language/UML
97
Information DEFinition Version 1x
IDEF1X
98
Chen notation is not standardized but often appears in literature and tools
Chen Notation
99
Strong Entity becomes a strong table. Primary key must be unique and non-NULL, and should be stable, simple, and meaningless. Single-column primary keys are best. but if no such columns exists, a composite primary key may have the required properties.
Strong Table
100
Single-Column primary key created by the database designer when no suitable single-column or composite primary key exists
Artificial Key
101
Subtype entity becomes a subtype table
Subtype Table
102
Weak entity becomes a weak table
Weak Table
103
Column A depends on Column B means each B value is related to at most one A value
Depends on
104
Dependence of one column on another
Functional Dependence
105
Entail dependencies between three or more columns
Multivalued dependence/Join Dependence
106
Reptition of related values in a table
Redundancy
107
Rules for designing tables with less redundancy
Normal forms
108
Every cell of a table contains exactly one value. The table has a primary key as well.
First normal form
109
When all non-key columns depend on the whole primary key
Second Normal Form
110
When all non-key columns depend on the key, the whole key, and nothing but the key.
Third Normal Form
111
Simple or composite column that is unique and minimal. Minimal means all columns are necessary for uniqueness
Candidate Key/Minimal
112
Column that is not contained in a candidate key
Nonkey
113
Whenever a non-key column A depends on column B, then B is unique. Columns A and B may be simple or composite
Third normal form
114
Whenever column A depends on Column b, then B is unique. Columns A and B may be simple or composite
Boyce-Codd Normal Form
115
Eliminates redundancy by decomposing a table into two or mote tables in higher normal form.
Normalization
116
Column A depends on column when each b value is related to at most one A value. A and B may be simple or composite columns
Depends On
117
If Column A depends on column B, then B must be unique
Boyce-Codd Normal Form
118
Intentionally introducing redundancy by merging tables
Denormalization
