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2. Introduction
to Databases
ACC09
PREPARED BY: LESTER B. DE ROMA

3. Prelim

4. What is
database?
 A database is an organized collection of data that can be accessed, managed,
and updated easily. It is a software system that allows users to store and
retrieve data from a central location. Databases are used in many areas, such
as business, healthcare, education, and more.
 A database consists of one or more tables, each of which contains records or
rows of data. Each row represents a unique instance of the entity being
modeled, such as a customer, employee, or product. Each column in a table
represents an attribute of the entity, such as name, address, or phone number.
 Databases are used to store and manage large amounts of data efficiently.
They allow users to retrieve data quickly and easily using queries, which are
written in a special programming language called Structured Query
Language (SQL).
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In addition to storing and retrieving data, databases also provide
features such as data validation, data integrity, and data security.
They allow users to ensure that data is accurate, consistent, and
protected from unauthorized access. Databases are essential tools
for businesses and organizations that need to manage and analyze
large amounts of data efficiently and effectively.

6. Data modeling and design.
 Data modeling and design are essential steps in the process of creating a
database. The goal of data modeling is to create a visual representation of the
data that will be stored in the database, while the goal of data design is to
determine how that data will be structured and organized within the database.
 Data modeling involves creating a conceptual model of the data that will be
stored in the database. This model includes a description of the entities or
objects that will be stored in the database and the relationships between those
entities. The data model is typically created using a graphical notation such as
an entity-relationship diagram (ERD).
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7. Entity-relationship diagram (ERD).
 The Entity-Relationship
Diagram (ERD) model is a
conceptual data model used
to represent the relationships
between entities. An entity is
a person, place, object,
event, or concept about
which data is stored.
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8. The ER model uses three main components:
entities, attributes, and relationships.
 Entities: Entities are objects that exist independently and can be
distinguished from other objects. For example, in a hospital database,
patients, doctors, and nurses are entities.
 Attributes: Attributes are characteristics or properties of entities. For
example, the name, age, gender, and address of a patient are attributes.
 Relationships: Relationships represent the associations between entities.
For example, a patient can have a relationship with a doctor, indicating that
the doctor is responsible for the patient's care.
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9. The ER model uses three main components:
entities, attributes, and relationships.
 Entities: Entities are objects that exist independently and can be
distinguished from other objects. For example, in a hospital database,
patients, doctors, and nurses are entities.
 Attributes: Attributes are characteristics or properties of entities. For
example, the name, age, gender, and address of a patient are attributes.
 Relationships: Relationships represent the associations between entities.
For example, a patient can have a relationship with a doctor, indicating that
the doctor is responsible for the patient's care.
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10. ER diagrams are used to represent the ER model. ER diagrams consist
of boxes (entities), ovals (attributes), and lines (relationships). The
diagram below shows an example of an ER diagram for a hospital
database.
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12. Thank you
“I don’t measure a man’s success
by how high he climbs, but how high
he bounces when he hits the
bottom.”
– George S. Patton