Databases

1
Databases

• Storage, Organize, Sharing gtgt DATA
• Examples
• 1. MS Access by Microsoft
• 2. Oracle by Oracle Inc.
• 3. DB2 by IBM
• 4. SQL Server by Microsoft

2
What is Data

• Data is an UNIT of information
• Data can be Text / Numeric / Both
• Examples
• Text Name of a person (John)
• Numeric Age of a person (21)
• Alphanumeric Unique ID (k2anandr)

3
Advantages

• Data is often COMPLEX
• SPEED of retrieval
• Scalable i.e. GROWTH SIZE
• COMPACT compared to paper based systems
• DISTRIBUTION

4
More about data

• Data is often VAGUE
• Example Consider text data Mickey
• Interpretations
• - Name of cartoon character
• - Name of pet
• - Name of friend

5
Business Reason

• History repeats itself
• Decision making
• Edge over competitors
• Case study Wal-Mart

6
Case Study (Wal-Mart)
MASTER DATABASE
7
Information

• A Collection or group of RELEVANT DATA
• Example Information about
• - Student (Western Michigan University)
• - Employees (General Motors)
• - Inventory (Amazon.com)

8
How Data is Organized

• Data is organized in the form of TABLES
• Tables are building blocks of a DB
• Rows Records
• Columns Fields
• Rows Columns intersect for data

9
Example
FIELDS (or) COLUMNS
ROWS (or) RECORDS
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Field Data types (Access)

• Recollect Types of data from previous slide
• Text Specify Length
• Number (Integer, Decimal etc)
• Date/Time (Short, Long etc)
• Currency
• Yes/No (Boolean, T/F)

11
Tables

• Provides easy organization of data
• Searching is faster
• Fields Requires unique name and type
• e.g. Cannot have two AGE columns
• No two Date of Birth columns
• Record Requires ATLEAST one unique identifier
• e.g. Social Security Number

12
Tables

• Unique identifiers are REQUIRED
• Reasons
• - Reduce duplicate data
• - Ease of organization
• - Faster storage and retrieval

13
Illustration
DATABASE
RECORDS
TABLES
14
START ACCESS

• Download tutorial files from my site
• http//homepages.wmich.edu/k2anandr