Transcript Principles of Database Design

Principles of
Database Design,
Part I
AIMS 2710
R. Nakatsu
File-Processing Systems
Problems with File-Processing
Systems
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Data are separated and isolated
Data are often duplicated
Incompatible data files
DBMS Relationships
The Relational Model
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Data is represented in two-dimensional tables
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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
What is a database?
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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:
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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
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Data definition
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Data manipulation
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You can select which data you want, filter it, sort it, join
it with other data, summarize it (querying data)
Data control
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Define what data is stored, the type of data, how the
data is related.
Specify how the data can be formatted and validated
Allows you to specify security, as well as how the data
can be shared.
Backup and recovery tools
Application Development
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Graphical tools to develop menus, forms, and reports