dbms Flashcards
➢ Are factual information such as
measurements or statistics about
objects and concepts. We use it for
discussions or as a part of a
calculation.
Data
➢ Is an organized collection of data,
typically stored in electronic
format. It allows you to input,
organize and retrieve data quickly.
Database
- It is representation of some aspect of
the real world. - Is logical, coherent and internally
consistent. - Is designed, built and populated with
data for specific purpose.
Properties of Database
➢ Is a collection of programs that
enables users to create and
maintain databases and control all
access to them.
Database Management System
➢ Is a programming language used
by all relational databases to
query, manipulate and define data
and to provide access control.
SQL Database
➢ Is a database designed to allow for
scalable data storage that can
handle. Compared to other
databases, NoSQL databases don’t
use tabular relationships
NoSQL Database
Programming Apps:
▪ mongoDB
▪ redis
▪ Cassandra
➢ Were used during 1970s-1990s.
This is a type of database system
that stores data in a single file or
table.
➢ Are basically text files, where
every line contains one records
and fields either have fixed
lengths or are separated with
commas, whitespaces and tabs.
Flat Files
➢ Were used in during the same era
stored data hierarchically arranged
manner.
o One-to-many Relationship
Hierarchical Database Systems
➢ Were introduced by Charles
Bachmann.
➢ Unlike hierarchical database
model, this database allows
multiple parent and child
relationships.
Network Databases
➢ In this database system, data is
stored in tables. The columns of
the table hold attributes of the
data. Each record usually has a
value for each attribute, making it
easy to establish the relationships
between data points
Relational Database System
➢ Unlike relational databases,
object-oriented databases work in
the framework of real
programming languages like Java
and C++, for example.
Object-oriented databases
- represents a realworld object such an
employee or a project.
Entity
– represents an
o association among entities.
Relationship
- Represents
data as
relations, or
tables.
Relational Data
Models
- Represents
data as record
types.
Network Data Models
- Represents as
a hierarchical
tree structure
Hierarchical Data
Models
o Is a framework for
organizing, storing and
managing data.
Data Structures
– typically work with
predefined queries and
switchboard commands, but also
use query languages to access
stored data.
Users
concerned with data security and
integrity preventing unauthorized
access, providing backup and
recovery, audit trails, maintaining
the database and supporting user
needs.
Database Administrators –
A DBMS can support several
related information systems that
provide input to, and require
specific data form the DBMS.
Related Information Systems –
controls database operations,
including storing, retrieving,
updating and deleting data.
Data Manipulation Language –
– the complete definition
of database, including
descriptions of all fields, tables,
and relationships
Schema
– is
also known as a data library or
data archive. This is a general
term to refer to a data set isolated
to be mined for data reporting and
analysis.
Physical Data Repository
– is person, place, thing or
event for which data is collected and
maintained.
Entity
– contains a set of
related records that store data about a
specific entity
Table or file
– also called an attribute, is a
single characteristic or fact about
entity
Field
– also called tuple (rhymes
with couple), is a set of related fields
that describes once instance, or
occurrence, of an entity, such as one
customer, one order or one product.
Record
– a field or
combination of fields that
uniquely and minimally
identifies particular member of
an entity
. Primary Key
– Any field
that could serve as a primary
key
Candidate Key
– A common field
that exists in more than one
table and can be used to form a
relationship, or link, between
the tables
Foreign Key
– A field or
combination of fields that can
be used to access or retrieve
records.
Secondary Key
– a set of rules
that avoids data inconsistency and
quality problems.
Referential Integrity
– abbreviated 1:1, exists
when exactly one of the second
entity occurs for each instance of the
first entity.
One-to-one
– abbreviated 1:M,
exists when one occurrence of the
first entity can relate to many
instances of the second entity, but
each instance of the second entity
can associate with only one instance
of the first entity.
One-to-many
– abbreviated M:N,
exists when one instance of the first
entity can relate to many instances if
the second entity, and one instance of
the second entity can relate to many
instances of the first entity.
Many-to-many
➢ Describes the numeric
relationship between two entities
and shows how instances of one
entity relate to instances of
another entity.
Cardinality
- is the process of
creating table designs by
assigning specific fields or
attributes to each table in
database.
o It involves applying set of
rules that can help you
identify and correct inherent
problems and complexities in
your table designs.
Normalization
o Starts with the name of the
table, followed by a
parenthetical expression that
contains the field names
separated by commas
Standard Notation Format
o Is a set of one or more fields
that can occur any number of
times in a single record, with
each occurrence having
different values.
Repeating Group
– an integrated
of collected data that can include
seemingly unrelated information, no
matter where it is stored in the
company.
Data Warehousing
– looks for meaningful
data patterns and relationships in
large amounts of data.
. Data Mining
– refers to data that
a user can view, understand, and
access, regardless of how or where
that information actually is organized
or stored
Logical Storage
– is strictly
hardware-related because it involves
the process of reading and writing
binary data to physical media such as
a hard drive, CD-ROM, or networkbased storage device.
Physical Storage
➢ A data model in which the data is
organized in relations (tables).
This is the model implemented in
most modern database
management systems.
Relational Model
➢ Pertaining to or constituting a
relationship between nodes in a
tree data structure in which parent
is one step closer to the root (that
is, one level higher) than the
child.
Parent/child Relationship
➢ Is a collection of related data
stored in centralized location or
repository.
➢ Typically hosted and managed
using a relational database
management system (RDBMS)
Relational Database
➢ Is a graphical representation of a
database design.
Entity-Relationship Diagram
– is the
process of designing
databases.
Data modelling
– establishes
entities, attributes and relationships.
Conceptual Design
– defines the
structure of data elements and
establishes relationship among data
elements.
o It adds a layer of detail to the
conceptual design by
defining the columns of data
that need to be included with
each entity
Logical Design
– describes
database-specific implementation
details and provides a blueprint for
the relational database.
o Includes additional details
about each column within an
entity.
Physical Design
Combines data into a single table to
remove external relationships and
dependencies. Though this approach can
speed up SQL queries, it also very often
results in redundant or duplicated data
throughout the database.
Denormalization
