Introduction to Relational Data Model
Summary
TLDRThis video introduces the relational data model, pioneered by Edgar Frank Codd in 1970, which revolutionized data storage and retrieval through table structures. It covers the history, including the first commercial implementations by Oracle and IBM's SQL/DS. The video also defines key RDBMS terminologies such as relation, tuple, attribute, domain, relation schema, degree, cardinality, and database schema. It explains how a relational database organizes data into tables and the importance of integrity constraints, setting the stage for learning SQL in subsequent chapters.
Takeaways
- đ The relational data model was introduced by Edgar Frank Codd (Ted Codd) in 1970, revolutionizing data storage and retrieval through tables with rows and columns.
- đĄ Relational databases are based on mathematical relations and use set theory as their theoretical foundation.
- đą The first commercial implementations of relational databases were by Oracle, followed by IBM with SQL/DS, which was IBM's first commercial RDBMS.
- đ SQL (Structured Query Language) became the standard language for interacting with commercial RDBMS systems.
- đ In RDBMS, data is organized into tables, where each table is referred to as a relation, and each row is known as a tuple.
- đ Attributes or fields are the column headers in a table, representing the characteristics of the data stored in the tuples.
- đ A domain in RDBMS defines the set of possible values that an attribute can take, ensuring atomicity and specifying data types.
- đ A relation schema describes a table by listing its attributes and their data types, providing a blueprint for the table's structure.
- đą The degree or arity of a relation refers to the number of attributes it contains, defining the dimensionality of the data structure.
- đ Cardinality represents the number of tuples or rows in a relation, indicating the size of the dataset at a given time.
- đ A relational database schema encompasses a set of relation schemas and integrity constraints, defining the overall structure and rules for a database.
- đ A relation instance or state represents the current set of tuples in a relation at a specific point in time, reflecting the database's dynamic nature.
Q & A
Who introduced the relational data model?
-The relational data model was introduced by Edgar Frank Codd, also known as Ted Codd, a computer scientist and mathematician.
What was the year when the relational data model was first introduced?
-The relational data model was first introduced in 1970.
What was Ted Codd's occupation when he invented the relational model?
-Ted Codd was working for IBM when he invented the relational model.
What is the fundamental concept of the relational data model?
-The relational data model is based on organizing data into tables with rows and columns.
What is the theoretical foundation of the relational data model?
-The relational data model is theoretically based on set theory and uses the concept of mathematical relations.
Which company was the first to commercially implement the relational model?
-Oracle was the first company to commercially implement the relational model.
What is the full form of SQLDS?
-SQLDS stands for Structured Query Language Data System, which was IBM's first commercial relational database management system.
What is the term used for a row in a relation?
-In a relation, each row is called a tuple.
What is a domain in the context of relational databases?
-A domain in relational databases is a set of values that are allowed for an attribute, and these values should be atomic.
What is a relation schema?
-A relation schema is used to describe a relation or a table, consisting of a relation name and a list of attributes, possibly including data types.
What is the degree or arity of a relation?
-The degree or arity of a relation is defined as the number of attributes in a relation schema.
How is cardinality defined in a relational database?
-Cardinality in a relational database is the total number of tuples or rows present in a relation.
What constitutes a relational database schema?
-A relational database schema is a set of relation schemas and a set of integrity constraints.
What is a relation instance or relation state?
-A relation instance or relation state is a set of tuples at a given moment of time.
Outlines
đ Introduction to Relational Databases
This paragraph introduces the concept of relational databases, starting with a brief history of their development. The relational data model was first introduced in 1970 by Edgar Frank Codd, a computer scientist and mathematician who worked for IBM. Codd's model revolutionized data storage and retrieval by organizing data into tables with rows and columns. The paragraph also discusses the theoretical basis of the model, which is rooted in set theory and mathematical relations. It mentions the first commercial implementations by Oracle and IBM, and the emergence of SQL as the standard language for RDBMS. The paragraph concludes with an introduction to key terminologies such as tables, relations, tuples, attributes, and domains, emphasizing their importance in understanding RDBMS.
đ Deeper Dive into RDBMS Terminologies
The second paragraph delves deeper into the terminologies associated with RDBMS. It explains the concept of a relation schema, which describes a table's structure, including its name and attributes, and may also specify data types. The paragraph introduces the terms 'degree' and 'arity' to describe the number of attributes in a relation schema. It also discusses 'cardinality,' which refers to the number of tuples or rows in a relation. The paragraph further explains the concept of a relational database schema, which is a collection of relation schemas and integrity constraints. It distinguishes between a relation state or instance, which represents the set of tuples at a given time, and how it can change with updates. The paragraph concludes with a summary of the terminologies discussed, reinforcing the viewer's understanding of RDBMS concepts.
Mindmap
Keywords
đĄRelational Data Model
đĄEdgar Frank Codd
đĄStructured Query Language (SQL)
đĄRelation
đĄTuple
đĄAttribute
đĄDomain
đĄRelation Schema
đĄCardinality
đĄRelational Database Schema
đĄRelation Instance
Highlights
Introduction to relational databases and the relational data model.
Historical background of the relational data model introduced by Edgar Frank Codd in 1970.
Codd's work at IBM and his invention of the relational model for data storage and retrieval.
The simplicity of the relational model in organizing data into tables with rows and columns.
The foundation of the relational model on mathematical relations and set theory.
Oracle's and IBM's early commercial implementations of the relational model.
Introduction of SQL/DS as IBM's first commercial relational database management system.
Popular RDBMS systems like SQL Server, Access, DB2, and Informix.
SQL as the standard language for commercial RDBMS.
Explanation of key RDBMS terminologies such as tables, relations, tuples, attributes, and domains.
Definition of a domain in the context of relational databases.
Relation schema as a description of a table, including its attributes and data types.
Degree or arity of a relation, which is the number of attributes in a relation schema.
Cardinality as the total number of tuples or rows present in a relation.
Relational database schema as a set of relation schemas and integrity constraints.
Relation instance or state as a set of tuples at a given moment in time.
The impact of updates on the relation state, such as adding or deleting tuples.
Conclusion of the video with a summary of the discussed terminologies in RDBMS.
Transcripts
hello everyone and welcome back to a new
chapter
in the course of dbms in this chapter we
are going to learn about relational
databases
so in this video we will be looking
mainly into the basic introduction to
relational data model
first let us look into a brief history
of relational data model
the relational data model was first
introduced in 1970
by a computer scientist and a
mathematician named edgar
frank god also called as ted cord
he was working for ibm when he invented
this relational model
in this model he gave a simple way of
storing data
as well as retrieving data via rows and
columns in a table
that is this model was all about
organizing data
into tables with rows and columns this
contribution of
ted cod had produced a dramatic or a
great
change and though he has made many other
contributions to computer science
this invention of his was his biggest
achievement
the relational data model uses the
concept of mathematical relations
and theoretically it is based on set
theory
the first commercial implementations of
the relational model
was by oracle and slowly even ibm
started to implement the same
and sqlds or structured query language
data system
was ibm's first commercial relational
database management system
the current popular rdbms or relational
database management systems
are the sql server and access from
microsoft
db2 and informix from ibm etc
an sql query language became the
standard language
for these commercial rdbms in the later
chapters we will be learning
sql query language in detail so that is
about the history of relational data
model
next let us learn few terminologies in
relation to
rdbms as i mentioned earlier
a relational database model organizes
data in the form of
tables or in other words a relational
model
represents data as a collection of
tables and here in rdbms
a table is also called a relation so
here i can say a relational model
represents data as a collection of
relations
in this table that i have taken student
is the relation name or the table name
and each row in the table
is called a tuple in this relation
student
we have two tuples or two rows
and each column or the column headers
are called as
attributes or fields in this relation
student
we have four attributes of four columns
hope you have understood these simple
terminologies
the next terminology that we are going
to learn is
domain a domain in mathematics is a set
of possible values that you can input
so similarly in relational database a
domain
is a set of values that are allowed for
an attribute and these values should be
atomic that
is each value in that domain is not
divisible further
for example a set of values for the
attribute name
should be a string of characters that
represent the name of
persons and here the values has to be
atomic
another example is domain for the
attribute employee ages
would be set of atomic values with
possible ages of
employees of a company allowed to be
between 20 and 70 years old
so hope you understood what a domain is
and domain
not only gives a set of values that are
allowed for an attribute
it also specifies the data type allowed
like for example the age has to be a
positive integer
next what is relation schema a relation
schema
is used to describe a relation or a
table
a relation schema is made up of a
relation name
which is denoted by a capital r and also
it is made up of a list of attributes
denoted as a1 a2 a3 a4
a5 and a6 you can also write a relation
schema by including the data types as
given over here
where name has to be a string roll
number has to be an integer
and so on next let us see what is degree
or
arity of a relation it is defined as the
number of
attributes in a relation schema we just
learned what a relation schema
is so in this example of the relation
schema that we just saw
the number of attributes is 6. therefore
the degree of this relation student is
6.
next what is cardinality cardinality
is the total number of tuples or rows
present in a relation
here i've taken a student relation with
attributes roll number
name and age so the cardinality of this
student relation is three because there
are three rows of three tuples
the next terminology that we are going
to see is relational database schema
a relational database schema is a set
of relation schemas and a set of
integrity constraints
that is if i take a company database the
relational database schema of that
company
would have a collection of relation
schemas like the employee relation
schema with the
employee details the department relation
schema
the project relation schema and so on so
a collection of all these relation
schemas along with the integrity
constraints
make up the relational database schema
for a company database
next what do you mean by a relation
state or relation database instance
a relation instance or a relation state
is a set of tuples at a given moment of
time
like for example say at time t 1 this is
the set of tuples at that given time
so this is the relation state or the
relation instance
suppose if i am updating this relation
by deleting this
third row then the set of tuples say at
time t2
would be only these two rows so that
would be the relation instance or the
relation state at that given time
so that's it with the terminologies in
relation to rdbms
with this we come to the end of this
video hope you have understood all that
we discussed in this video
thank you
you
Voir Plus de Vidéos Connexes
Part3 : Database Testing | How To Test Schema of Database Table | Test Cases
Coddâs 12 Rules (13 Rules)
Lec-2: Introduction to DBMS (Database Management System) With Real life examples | What is DBMS
Introduction to Databases
02-01-relational-model.mp4
Was ist ein Relationales Datenbankmodell? - einfach erklÀrt!
5.0 / 5 (0 votes)