Principles ofDatabase Design,

Part I

AIMS 2710

R. Nakatsu

File-Processing Systems

Problems with File-Processing Systems

Data are separated and isolated Data are often duplicated Incompatible data files

DBMS Relationships

The Relational Model

Data is represented in two-dimensional tables Each of the tables is a matrix consisting of a

series of row/column intersections Files are called tables or relations Fields (i.e. columns) of the tables are called

attributes Records (i.e. rows) of the tables are called

tuples (rarely used terminology) Information in more than one table can be

easily extracted and combined

Table Row Column

File Record Field

Relation Tuple Attribute

Related Terminology: Three ways to refer to the same thing

What is a database?

A database is an integrated collection of logically related data elements. A database consolidates records previously stored in separate files.

A database can be viewed as the topmost element of a data hierarchy: database (a set of related files) file (a collection of related records) record (a group of logically related fields) field (an attribute) character (single alphabet, number, or other symbol)

Database Management System (DBMS)

A DBMS (database management system) is a set of computer programs that is used to create, maintain, and provide controlled access to user databases

What are some of the DBMS products on the marketplace today?

DBMS: Main Functions Data definition

Define what data is stored, the type of data, how the data is related.

Specify how the data can be formatted and validated Data manipulation

You can select which data you want, filter it, sort it, join it with other data, summarize it (querying data)

Application Development Graphical tools to develop menus, forms, and reports

Data control Allows you to specify security, as well as how the data

can be shared. Backup and recovery tools