Introduction to Databases

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Introduction to Databases

• CISC 1050

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Where would you find info about yourself stored
in a computer?

• College
• Physicians office
• Library
• Grocery Store
• Dentists office
• Verizon
• IRS

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General Definition

• A DATABASE is a collection of related data.
• Data known facts that can be recorded and have
  implicit meaning.

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Example of a Database
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Size of a database

• Small database example
• your personal phone directory
• Large database example
• database of the IRS

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DBMS Database Management System

• A collection of programs that enables users to
  create and maintain a database.

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MS Access is a DBMS

• In ACCESS, a DATABASE consists of a collection
  of tables.

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Table

• A table is defined by its columns, called fields.
• Each row (or entry) in a table is called a
  record. A record is the information about a
  specific person, product, or event.

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Starting ACCESS

1. Begin ACCESS
2. Create a blank Database although a database
   consists of many files, in Access, each database
   is viewed as a single file, hence a single icon.

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Navigation Pane and Work Area

• Navigation Pane On the left you will see a list
  of the objects in the database (including tables,
  forms, reports, queries, etc.)
• Work Area on the right you have the object you
  are currently working on.

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Defining a TABLE

• A TABLE is defined by its fields (column
  headings).
• Field Name unique name
• Data Type type of info a field can
  contain.
• Description comments about field.

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PRIMARY KEY

• Each table must have a primary key which is a
  unique identifier for each record.
• Eg. ID number for a student, course number for a
  course, driver number for a driver, etc.

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Two VIEWS of a Table

1. Design View view the tables definition, I.e.
   the fields and their properties.
2. Datasheet View view the actual records in the
   table.

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Database Design

• Arranging data into tables and fields.
• This process can be long and difficult.

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Remove Redundancy

• WHY?
• Wastes space
• Updating is difficult
• Inconsistent data may result