stored representations of meaningful objects and events

data processed to increase knowledge in the person using the data

data that describes the properties and context of user data

All programs maintain metadata for each file they use

Different systems/programs have separate copies of the same data

No centralized control of data

Programmers must design their own file formats

80% of information systems budget

SOLUTION: THE DATABASE APPROACH EXCEPT

Database management system A software system that is used to create, control, and provide controlled access to user databases

advantages of the database approach (two answer)

cost and risk of the database approach (more than one answer)

Data models

– Graphical system capturing nature and relationship of data

– Enterprise Data Model–high-level entities and relationships for the organization

– Project Data Model–more detailed view, matching data structure in database or data warehouse

Entities

– Noun form describing a person, place, object, event, or concept

– Composed of attributes

computer-aided software engineering

Respiratory is acentralized storehouse of data

DBMS meaning

Database–storehouse of the metadata

software using the data

text and graphical displays to users

what are the approaches to database and IS development

E-R model constructs

a person, a place, an object, an event, or a concept in the user environment about which the organization wishes to maintain data

A single occurrence of an entity type

Composite attribute - An attribute that has meaningful component parts (attributes)

may take on more than one value for a given entity (or relationship) instance

Cardinality of relationships

Degree of relationships

Degree of relationship

extends original ER model with new modeling constructs

A subgrouping of the entities in an entity type that has attributes distinct from those in other subgroupings

Generalization: The process of defining a more general entity type from a set of more specialized entity types. TOP-DOWN

Specialization: The process of defining one or more subtypes of the supertype and forming supertype/subtype relationships. BOTTOM-UP

Yes (double line) - A rule that specifies that each entity instance of a supertype must be a member of some subtype in the relationship.

No (single line) - A rule that specifies that an entity instance of a supertype is allowed not to belong to any subtype.

Whether an instance of a supertype may simultaneously be a member of two (or more) subtypes

a simple attribute with alternative values to indicate the possible subtypes

Whether an instance of a supertype must also be a member of at least one subtype

a composite attribute whose subparts pertain to different subtypes. Each subpart contains a Boolean value to indicate whether or not the instance belongs to the associated subtype

Set of one or more entity types and associated relationships grouped into a single abstract entity type

The relational data model represents data in the form of choices.

Tables (relations), rows, columns

Powerful SQL operations for retrieving and modifying data

Allowable values for an attribute (See Table 4-1). A domain definition usually consists of the following components: domain name, meaning, data type, size (or length), and allowable values or allowable range (if applicable).

E-R attributes map directly onto the relation

Use only their simple, component attributes

Becomes a separate relation with a foreign key taken from the superior entity

Data normalization is a Primarily a tool to validate and improve a logical design so that it satisfies certain constraints that avoid unnecessary duplication of data

adding new rows forces user to create duplicate data

deleting rows may cause a loss of data that would be needed for other future rows

changing data in a row forces changes to other rows because of duplication

Candidate key is an attribute, or combination of attributes, that uniquely identifies a row in a relation.

Nonredundancy - For every row, the value of the key must uniquely identify that row. This property implies that each nonkey attribute is functionally dependent on that key

Unique identification - No attribute in the key can be deleted without destroying the property of unique identification

if new product is ordered for order 1007 of existing customer, customer data must be re-entered, causing duplication

if we delete the Dining Table from Order 1006, we lose information concerning this item’s finish and price

changing the price of product ID 4 requires update in multiple records

Relationships at the subtype level indicate that all subtypes will participate in the relationship

The instances of a supertype may participate in a relationship unique to that subtype.