Database Design

What is Program-Data Redundancy?

What is Data Redundancy?

What is Data Inconsistancy?

What is Data Anomalies?

Data Dictionary Management - Data dictionary: Stores [blank_start]definitions[blank_end] of the [blank_start]data[blank_end] [blank_start]elements[blank_end] and their [blank_start]relationships[blank_end]

[blank_start]Data storage management[blank_end] - Performance tuning: Ensures [blank_start]efficient[blank_end] [blank_start]performance[blank_end] of the [blank_start]database[blank_end] in terms of [blank_start]storage[blank_end] and access [blank_start]speed[blank_end]

[blank_start]Data transformation and presentation[blank_end] - Transforms entered data to conform to required data structures

[blank_start]Security management[blank_end] - Enforces user security and data privacy

[blank_start]Multiuser access control[blank_end] - Sophisticated algorithms ensure that multiple users can access the database concurrently without compromising its integrity

[blank_start]Backup and recovery management[blank_end] - Enables recovery of the database after a failure

[blank_start]Data integrity management[blank_end] - Minimizes redundancy and maximizes consistency

[blank_start]Database[blank_end] [blank_start]access[blank_end] [blank_start]languages[blank_end] [blank_start]and[blank_end] [blank_start]application[blank_end] [blank_start]programming[blank_end] interfaces - Query language: Lets the user specify what must be done without having to specify how • Structured Query Language (SQL): De facto query language and data access standard supported by the majority of DBMS vendors

[blank_start]Database communication interfaces[blank_end] - Accept end-user requests via multiple, different network environments

Abstraction of a real-world object or event is an example of Data Models?

Collection of related concepts used to describe the structure of a database, i.e. unique objects, data types, relationships, and constraints • Useful for supporting a specific problem domain • Simple representations of complex real-world data structures This is an example of Data Modelling

A Model refers to the process of creating a specific data model for a determined problem domain.

An [blank_start]entity[blank_end] is a person, place, thing, or event about which data will be collected and stored.

An [blank_start]attribute[blank_end] is a characteristic of an entity

A [blank_start]relationship[blank_end] describes an association among entities.

A [blank_start]constraint[blank_end] is a restriction placed on the data

• Logical Data Independence:

Data Independence:

Physical Data Independence:

[blank_start]Primary Key[blank_end] - An attribute that can identify each row in a table uniquely. Cannot be null or duplicate

[blank_start]Composite Primary Key[blank_end] - Composed of more than one attribute

[blank_start]Secondary Key[blank_end] - Unique key other than primary key, Strictly for data retrieval purposes, E.g. Customers do not remember their ID, but they do remember their phone number!

[blank_start]Entity integrity[blank_end] - Each row (entity instance) in the table has its own unique identity

[blank_start]Foreign key[blank_end] - An attribute whose values match primary key values in the related table

[blank_start]Referential integrity[blank_end] - FK contains a value that refers to an existing valid tuple (row) in another relation

[blank_start]UNION[blank_end] will show all rows in the tables except duplicates

[blank_start]UNION ALL[blank_end] will show all rows from the tables including duplicates

[blank_start]PROJECT[blank_end] - Unary operator that yields a vertical subset of a table. Yield all values for selected attributes

[blank_start]INTERSECT[blank_end] - Yields only the rows that appear in both tables

[blank_start]DIFFERENCE[blank_end] - Yields all rows in one table that are not found in the other table

[blank_start]Identifiers[blank_end]: one or more attributes that uniquely identify each entity instance.

[blank_start]Composite attribute[blank_end]: Attribute that can be subdivided to yield additional attributes

[blank_start]Simple attribute[blank_end]: Attribute that cannot be subdivided

[blank_start]Single valued attribute[blank_end]: Attribute that has only a single value.

[blank_start]Multivalued attribute[blank_end]s: Attributes that have many values.

[blank_start]Derived attribute[blank_end]: Attribute whose value is calculated from other attributes