Week 1: Review of Database & SQL

Data

Raw facts, or facts that have yet been processed to reveal their meaning to the end user.

Information

The result of processing raw data to reveal its meaning.

Database

A shared, integrated computer structure that houses a collection of related data (end-user data and metadata).

Database Management System

A collection of programs that manages the database structure and controls access to the data stored in the database.

Components of the DBMS environment

1. Data

2. Hardware

3. Software

4. End Users

5. Procedures

DBMS facilities

1. Data Definition Language (DDL)

2. Data Manipulation Language (DML)

3. Security system

4. Integrity system

5. Concurrency control system

6. Recovery control system

Entity Relationship Model

A graphical representation of entities and their relationships in a database structure (introduced by Peter Chen in 1976).

Types of relationships

• One-to-One (1:1)

• One-to-Many (1:*)

• Many-to-Many (:)

Structured Query Language (SQL)

Structured Query Language; the standard language used to define, query, update, and maintain relational databases.

SQL Command Categories

• DDL (CREATE, ALTER, DROP)

• DML (SELECT, INSERT, UPDATE, DELETE)

• DCL (GRANT, REVOKE)

• TCL (COMMIT, ROLLBACK)

Primary Key

An attribute or field that serves as a unique identifier for a record within a relation.

Normalization

A process of reducing data redundancy in a database.