0:00	foreign
0:06	welcome back algebra is one of the broad
0:10	areas of mathematics we would have come
0:13	across various algebra branches let's
0:16	take abstract algebra where the abstract
0:18	algebra is to study the algebraic
0:20	structures such as groups Rings fields
0:24	and abstract algebra has its wide
0:26	application area in the field of
0:28
cryptography coming to linear algebra
0:30
linear algebra deals with the linear
0:33
equations linear mappings and is used in
0:36
the application area like the weather
0:37
forecasting coming to Boolean algebra
0:40
these Boolean algebra deals with the
0:42
variables that are with the truth values
0:44
true or false and Boolean algebra has
0:47
its widespread applications in the areas
0:50
of digital circuitry designed in
0:52
personal computers pocket calculators CD
0:55
players cell phones and other electronic
0:58
products one such algebra that we are
1:00
going to focus in today's presentation
1:02
is the relational algebra and in today's
1:05
presentation we are going to focus on
1:07
the basics of relational algebra while
1:11
waiting let's step into the topic of the
1:13
day the relational algebra and
1:15
relational algebra is basically a
1:18
procedural query language what do we
1:20
mean by this it means we need to
1:22
instruct what to do how to do we are
1:25
expecting the result from the database
1:27
and the result is going to be a table or
1:29
a relation and in order to get that
1:32
result the table or the relation we need
1:34
to instruct what is required and how to
1:37
retrieve that data or how to retrieve
1:40
the result and that is why we refer
1:42
relational algebra as a procedural query
1:44
language if you are directly watching
1:46
this lecture I request you to navigate
1:48
to chapter 1 of this playlist and find
1:51
the lecture database languages where I
1:53
have explained about the database
1:55
languages the procedural query language
1:57
and the non-procedural query language
1:59
with examples for now just understand
2:02
relational algebra is a procedural query
2:05
language and what it actually does
2:07
basically a relational algebra is a set
2:10
of operations on relations this is like
2:13
the normal algebraic operation where
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it's going to take input and it's going
2:17
to produce the output likewise here also
2:20
relational algebra is basically a set of
2:23
operations on relations so it's going to
2:26
work on the relation and does the
2:28
operation and gives the result as a
2:30
relation only and that's why we say
2:32
relational algebra is basically a set of
2:35
operations and to be precise it is like
2:38
a set of algebraic operations these
2:41
algebraic operations like the addition
2:43
subtraction all these take some values
2:45
as the input and does the operation and
2:47
produces the output likewise here also
2:50
relational algebra is going to take
2:51
relations as input does the operation
2:54
and generates the output which is also a
2:56
relation in simple terms relational
2:58
algebra is a set of operations which
3:01
takes one or more relations as input and
3:03
produces a relation as an output so so
3:06
that's what the next Point says the
3:08
input is going to be one or more
3:10
relations and the output is going to be
3:12
a relation and why one or more relations
3:15
there are certain relational algebra
3:17
operators which are unary operators
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where it takes only one relation as an
3:22
input there are certain relational
3:23
algebra operators with takes two or more
3:26
inputs so they are binary or ternary so
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what I mean to say is in a nutshell it
3:31
takes one or more relations as an input
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and produces another relation as an
3:36
output and why do we need to study this
3:38
relational algebra because it provides a
3:41
theoretical foundation for relational
3:43
databases we know the power of
3:45
relational databases in this
3:47
contemporary world when we want to work
3:49
on the relational database or when we
3:51
want to know the foundations of the
3:53
relational database it's always
3:54
recommended to have a sound knowledge on
3:57
relational algebra because it provides a
4:00
theoretical foundation for the
4:02
relational databases the well-known dbms
4:05
language that is widely used in today's
4:07
world is the structured query language
4:09
SQL and when you want to become
4:11
proficient with SQL knowing relational
4:13
algebra will give an additional
4:15
advantage and not only that when we have
4:18
a sound knowledge in the relational
4:20
algebra obviously it allows us to
4:23
understand database operations in more
4:25
detail and also it motivates us to write
4:28
optimized queries we know databases are
4:31
going to respond to queries when we
4:33
Supply a query to the database database
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accepts the query does the operation and
4:38
gives the result if we want to get that
4:40
output there may be multiple ways if we
4:43
want an output from the database I mean
4:45
a relation or a table there can be
4:47
multiple queries where these queries
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gives the same output but giving an
4:51
optimized query is always good because
4:54
your databases will not take more time
4:56
or more memory to execute that query so
4:59
what I mean to say is instead of giving
5:01
a query to the database if we give an
5:04
optimized query the database will
5:06
respond easily because this optimized
5:09
queries will be having lower cost cost
5:11
is one of the factors that are used to
5:13
measure the query optimization in simple
5:15
terms relational algebra helps us to
5:18
write optimized queries and also it
5:21
helps us to understand the database
5:22
operations in more detail what's
5:24
happening at the back end how queries
5:26
are processed how query execution plans
5:29
are generated how the plans are executed
5:31
all these things no worries in the
5:34
coming lectures we are going to focus on
5:35
query optimization techniques at the
5:37
time I will explain you how query
5:39
optimization is actually taken care by
5:41
database we are done with the basics of
5:44
relational algebra before we move on to
5:47
the next slide just revisit what is
5:49
relational algebra it is a set of
5:51
operations what are the operations that
5:54
relational algebra contains that's what
5:56
we are going to see now basically the
5:58
relational algebra operations are
6:00
classified into two categories number
6:02
one the fundamental operations and
6:05
number two the additional operations
6:06
let's just focus on the names of the
6:08
operations in this lecture in the coming
6:10
lectures we are going to focus on all
6:13
the operations one by one in detail with
6:16
required examples for now let's just
6:18
know the operation names talking about
6:21
the fundamental operations there are six
6:23
fundamental operations as far as
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relational algebra is concerned the
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first operation is select the second
6:29
operation is Project the third one is
6:32
Union the fourth one is the set
6:34
difference fifth one is the Cartesian
6:36
product and the last fundamental
6:38
operation in relational algebra the
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sixth one is the rename operation
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these six operations are the fundamental
6:46
operations in relational algebra and
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coming to the additional operations we
6:51
have various additional operations in
6:53
relational algebra they are the set
6:55
intersection operation the assignment
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operation the inner join where in inner
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joint we are going to focus on the
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natural join equi join and Theta join
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but our emphasis in this subject will be
7:07
more on natural joint and the next
7:10
additional operation is the division
7:11
operation and the last additional
7:13
operation that we are going to focus on
7:15
in this subject is the outer join where
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we are going to see three forms of Auto
7:20
join the left outer join the right outer
7:23
join and the full outer join so we have
7:26
seen about the various fundamental and
7:28
additional operations in the coming
7:30
lectures we are going to focus on all
7:33
the operations one by one with examples
7:35
and that's it guys I hope you guys
7:37	enjoyed this presentation and thank you
7:40	for watching
7:41	[Music]
7:41	[Applause]
7:43	[Music]