Table of content#

• Review Week5 Tutorial.
• Introduction to Databases.
• Introduce SQL.
• Downloading MySQL.

Introduction#

• What is a Database?
  • A collection of related and organized data designed to meet the information needs of an organization.
• Database is a structured object.
  • Data is the actual stored descriptive information.
  • Metadata is the structured part (table definition).

NOTE

In XML, metadata is something like attribute

Examples of Using Database Systems#

• Scientific Data Collection.
• Purchases from the supermarket.
• Purchases using credit card, generation of monthly statements.
• Using the local library.
• Taking out insurance.
• At universities.
• Booking a holiday at the travel agents.

Components of a Database System#

• The components of a database system are:
  • Users.
  • Database Application.
  • Database Management System (DBMS).
  • Database.
  • Data.

Users: A user of a database system will

• Use a database application to track things.
• Use forms to enter, read, delete and query data.
• Produce reports.

Database Application:

• A set of one or more computer programs that serves as an intermediary between the users and the DBMS.
• Application program read or modify database data by sending SQL statements to DBMS.
• Application program present data and processes quires to users in the format of forms and reports.

• Database management systems (DBMS) relate to information stored in tabular formats.
• The DBMS manages the interaction between the end user and the database.
• DBMS receives request encoded in SQL and translates these requests into actions on the database.
• Companies almost never write their own DBMS program.
• They rather use licensed softwares.

DBMS#

• Why is DBMS needed?
  • Improves decision making.
  • Increases end-user productivity.
  • Minimizes data redundancy.
  • Enforces standards.
  • Maintains the privacy/confidentiality.
  • Reduces program maintenance.

Types of Database Systems#

• Number of Users
  • Single-user: Desktop database.
  • Multiuser: Workgroup database, Enterprise database.
• Scope/limitation:
  • Desktop, Workgroup, Enterprise.
• Location:
  • Centralized database, distributed database.

The Database Administrator (DBA)#

• Works with programmers and analysts to design and implement the database.
• Works with users and managers to establish database policies.
• Implements security features and establishes database permissions

Relational Database Model#

• Relational algebra allows us to use mathematical logic to create a relationship between a few tables.
  • So we can retrieve data efficiently.
  • Any table can be accessed directly without having to access all parent objects.
  • Any tables can be linked together, regardless of their hierarchical position.

Major Database Concepts#

• Data: Raw facts about things and events.
• Information: Processed data or transformed data that has value for decision making.
• Metadata: Data about data, or the database definition or descriptive information.
• The instance: The collection of information stored in the database at a particular moment is called an instance of the database.
• Database Schema: The overall design of the database.

SQL#

• SQL (Structured Query Language).
• Is a domain-specific language used in programming and managing data held in a relational database management system (RDBMS).
• SQL is a declarative programming language.

Data types#

• Some strings
  • Char(10)
  • Varchar(50)
• Date types
  • Date
  • Time
  • Datetime
• Some Numerics
  • TinyInt
  • SmallInt
  • MediumInt
  • Int
  • BigInt
  • Float (5,2)
  • Decimal (5,2)
  • Signed
  • Unsigned