Introduction to Relational Data Model

Summary

This 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

• 📚 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.
• 💡 Relational databases are based on mathematical relations and use set theory as their theoretical foundation.
• 🏢 The first commercial implementations of relational databases were by Oracle, followed by IBM with SQL/DS, which was IBM's first commercial RDBMS.
• 🔍 SQL (Structured Query Language) became the standard language for interacting with commercial RDBMS systems.
• 📊 In RDBMS, data is organized into tables, where each table is referred to as a relation, and each row is known as a tuple.
• 🔑 Attributes or fields are the column headers in a table, representing the characteristics of the data stored in the tuples.
• 🌐 A domain in RDBMS defines the set of possible values that an attribute can take, ensuring atomicity and specifying data types.
• 📝 A relation schema describes a table by listing its attributes and their data types, providing a blueprint for the table's structure.
• 🔢 The degree or arity of a relation refers to the number of attributes it contains, defining the dimensionality of the data structure.
• 📈 Cardinality represents the number of tuples or rows in a relation, indicating the size of the dataset at a given time.
• 📋 A relational database schema encompasses a set of relation schemas and integrity constraints, defining the overall structure and rules for a database.
• 🕒 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

00:00

📚 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.

05:00

🔍 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.

Keywords

💡Relational Data Model

The relational data model is a method of organizing data using a tabular structure of rows and columns, where each row represents a unique instance and each column represents an attribute. Introduced by Edgar Frank Codd in 1970, it revolutionized data storage and retrieval by simplifying the way data is accessed and managed. In the video, the relational data model is the central theme, with a focus on how it organizes data into tables, which are essentially relations.

💡Edgar Frank Codd

Edgar Frank Codd, also known as Ted Codd, is a computer scientist and mathematician credited with the invention of the relational data model. His work at IBM led to a breakthrough in database management systems, making him a pivotal figure in the field of computer science. The video script highlights his significant contribution to the development of the relational model, which is his most notable achievement.

💡Structured Query Language (SQL)

Structured Query Language, or SQL, is a domain-specific language used in programming and managing data held in a relational database management system (RDBMS). It is the standard language for RDBMS and is used for various tasks such as data query, data manipulation, and data access control. The video mentions SQL as the standard language for commercial RDBMS, indicating its importance in managing relational databases.

💡Relation

In the context of the relational data model, a relation is a set of tuples (rows) with the same attributes (columns). It is essentially a table that represents a collection of data. The video script uses the term 'relation' to describe the structure of data in a database, emphasizing that each table in an RDBMS is a relation with its own set of tuples and attributes.

💡Tuple

A tuple in a relational database is a single instance of data, represented as a row in a table. Each tuple contains values for each attribute (column) of the relation (table). The video script explains that each row in a table is called a tuple, providing a clear example with a 'student' relation that contains two tuples.

💡Attribute

An attribute in a relational database is a column in a table that represents a specific characteristic of the data. It defines the type of data that can be stored in that column. The video script mentions attributes as the column headers in a relation, such as 'roll number', 'name', and 'age' in the 'student' relation, which are all attributes.

💡Domain

A domain in a relational database refers to the set of possible values that an attribute can take. It defines the constraints on the data that can be entered into a particular field, ensuring data integrity. The video script explains that domains are atomic, meaning the values they contain cannot be divided further, and they also specify the data type for each attribute.

💡Relation Schema

A relation schema is a blueprint that defines the structure of a relation, including the names and data types of its attributes. It serves as a template for creating actual relations in a database. The video script describes a relation schema as consisting of a relation name and a list of attributes, which helps in understanding the organization of data within a table.

💡Cardinality

Cardinality in a relational database refers to the number of tuples (rows) present in a relation (table). It is a measure of the size of a relation. The video script uses the term to illustrate the total number of rows in a 'student' relation, which is three, indicating the relation's cardinality.

💡Relational Database Schema

A relational database schema is a collection of relation schemas and integrity constraints that define the structure of a database. It encompasses all the tables, their attributes, and the rules that govern the data within them. The video script mentions that a company database's schema would include various relation schemas, such as employee, department, and project schemas, along with their respective integrity constraints.

💡Relation Instance

A relation instance, also known as a relation state, is a snapshot of the tuples (rows) in a relation (table) at a specific point in time. It represents the current state of the data. The video script explains this concept by showing how the set of tuples in a 'student' relation changes over time, such as when a row is deleted, thus altering the relation 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