Introduction to Databases CIS 5 2 Where would

Introduction to Databases CIS 5. 2

Where would you find info about yourself stored in a computer? • • College Physician’s office Library Grocery Store Dentist’s office Verizon IRS …

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

Example of a Database

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

DBMS – Database Management System A collection of programs that enables users to create and maintain a database.

MS Access is a DBMS In ACCESS, a DATABASE consists of a collection of tables.

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.

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.

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.

Defining a TABLE A TABLE is defined by its fields (column headings). 1. Field Name – unique name 2. Data Type – type of info a field can contain. 3. Description – comments about field.

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.

Two VIEWS of a Table 1. Design View – view the table’s definition, I. e. the fields and their properties. 2. Datasheet View – view the actual records in the table.

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

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