Unit 1 - Databases

Question 1

What is a Database?

Answer 1

Any collection of data
Paper, spreadsheet, formal database

Question 2

Goals of a Database

Answer 2

secure
consistent
integrity
maintained

Question 3

Database Management System (DBMS)

Answer 3

Layer between users and data
Hides how data is stored
separates logic from data
backup/recovery
maintains constraints
role-based access

Question 4

ACID

Answer 4

Atomicity - Transactions either happen fully or not at all
Consistency - The database is always in a valid state
Isolation - Concurrent accesses should stay independent
Durability - System failures don’t destroy the database

Question 5

Schema

Answer 5

A description of the data model
Name of tables and columns

Question 6

Instance

Answer 6

A snapshot of the database at a specific point in time

Question 7

View

Answer 7

A piece of the database (or the result of a query) the user is shown