Introduction to Databases CISC 1050

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 unique identifierEach 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