ch 12.txt

Information systems are software applications that facilitate the organization and analysis of data.

Spreadsheet software allows users to place raw data in tables and then utilize formulas and basic graphical mechanisms to generate calculations and illustrations from it.

alternative

• From outside in:
• Database (the stored data of the system)
• Database management system (system of programs controlling how data is accessed)
• Application software (system of programs specifying how to present data to the user)

Tuples are rows (records) and columns are attributes (fields).

It is a query. It removes rows (from your view) that don't meet the criteria. Or, it determines which tuples have particular attributes.

It limits the view of the database to particular columns (attributes).

It combines multiple tables that have common attributes.

It refers to the possibility of the loss of data integrity due to concurrent access to data from multiple access points. It can be avoided by locking records, and by setting rollback points to recover database to its state prior to transaction being processed.

It is encoding a message in such a way that only the receiving station can decode it.

• 1) create message
• 2) look up recipient's public key
• 3) encrypt message with recipient's public key
• 4) transmit encrypted message
• 5) decrypt message with recipient's private key

Authentication is validating that the message sender is who it appears to me.

• 1) create message
• 2) encrypt message with sender's private key
• 3) transmit encrypted message
• 4) decrypt message with sender's public key