Chapter 5 ACIS
Database Processing
1. What is the purpose of a database?
-to keep track of things
-lists that involve single theme: spreadsheet
-lists that involve multiple themes: database
2. What is a database?
Database: self-describing collection of integrated records
Byte: character of data
- Bytes grouped into columns
oColumns grouped into rows called records
Group of rows or records is called table or file
Database is collection of tables plus relationships among rows in those tables plus special data, called
metadata, that describes structure of the database
- What are relationships among rows?
oKeys : column or group of columns that identifies a unique row in a table
oForeign key : columns which are keys of a different (foreign) table than the one in which
it resides
oRelational database : databases that carry their data in the form of tables and represent
relationships using foreign keys
- Metadata : data that describe data
- Enterprise DBMS vs Personal DBMS
oEnterprise DBMS products process large organizational and workgroup databases
24/7 operations
Can manage databases that span dozens of different magnetic disks with
hundreds of gigabytes or more data
oPersonal DBMS products designed for smaller, simpler database applications
Fewer than 100 users, normally single
Ex: student database
3. How are data models used for database development?
Data Model: describes data and relationships that will be stored in the database; like a blueprint
Entity-relationship data model: tool for constructing data models
- Describes content of a data model by defining the entities stored in the database and the
relationships among those entities
Unified Modeling Language (UML): less popular tool for data modeling
Entity: some thing that users want to track
- Ex: order, customer, item
oSome represent physical object (item or customer), others represent logical construct or
transaction (order or contract)
