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[Music]
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hello friends welcome back to our
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channel
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so
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today we will discuss about the
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introduction to rdbms and the basic
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terminologies
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in rdbms
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so this rdbms stands for
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relational
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database management system relational
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dbms
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and the name itself indicates
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it will deal with the
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relations
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all the relations
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so here the relations means the data is
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represented
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data will be represented in terms of
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rows
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in
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rows right so the data here the rate
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will be represented in terms of rows and
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that we call it as a relations right so
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organizing the data in tables will be
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very easy to access the data right if
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any sort of the data is organized in the
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form of tables then automatically it
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will be very easy for
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accessing that particular data so that's
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why so this is a relational database and
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a modern softwares
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will be using
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related to this relational database
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management system that is a relational
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dbms rdbus now we will see the basic
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terminologies of this rdbms
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so the first one
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is
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a relation
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so what is meant by this relation in
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rdbms
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so this relation means
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table
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table is also known as a relation in
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rdbms for example consider the student
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database so student table
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so student id
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student name
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percentage
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percentage so
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this is the
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a table this is called a table or a
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relation
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it's called a
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relation
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for example student number is 101 and
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the student name is some sandi
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and the percentage is some 95
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and the student
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number is one or two
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and name is samsara
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and some percentage is 94
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and 103 the student name is
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some
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deepak
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and the percentage is some 90 right so
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this is the student table this is a
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student
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table
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and this we call it as a relation in rdm
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or dbms so here you can see we are
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giving the student details all the
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student details are being organized in a
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tabular format so that's why we call it
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as a relation
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right so relation means a table
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which consists of rows and columns and
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data
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and the second terminology is
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tuples
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or
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records
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records so the individual row is known
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as a tuple so if you observe
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so this is
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one tuple
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and this is another triple
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and this is an another tuple or we can
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also call as a records so for example
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you can see here
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so this particular row consists of the
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details of a student sunday the second
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row consists of the details of a student
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sarah
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third row consists of the student
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details related to a deeper right so
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that means we are having three
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rows we are having some three student
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details right each row is known as a
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tuple or a record so here we we need to
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remember a few things that is in tuple
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there should be no duplicate values
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no duplicate tuples right
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that means identical tuples should not
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be included in the relation for example
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we are having a fourth row one not one
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and sandeep and 95 so if you observe
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here the fourth row the fourth row is
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having the unique elements of the first
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row so one not one ninety five one hour
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comes only 95 so
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this should not be accepted that means
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no duplicate tools should be available
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right and
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so all the tuples should follow
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same format
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same format that means the first one
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student id student name and percentage
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so the same format should be followed
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for all the students
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right and the next terminology so these
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are called as a tuples right these are
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called as a tuples and i am removing
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this one
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so no duplicate should be allowed in
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tuples right
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now
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next one
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attributes
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attributes and these attributes are
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known as
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the columns okay the columns so
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this is an attribute
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and this is an attribute
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this is an
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attribute so attributes are for the
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tuples so you can observe that user
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first attribute should have a name
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attribute
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should have
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a name to identify to name
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should have a name to identify so here
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student id is an attribute
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student name is an attribute percentage
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is an attribute so here i am writing
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student
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name is an attribute
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sorry student id the first one is id
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then student
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name is one more attribute
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percentage
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is one more item so every attribute
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should have a name to identify
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right and also
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there will be a unique attribute
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unique attribute
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known as a primary key
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primary key to identify the tuples okay
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to identify the tuple
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there should be a unique attribute
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called as a primary key
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right for example if you take student
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name so sandi so
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in a class
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there can be multiple students with the
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same name
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so it should not be considered as a
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primary key
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coming to the percentage so more than
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one student can get a equal percentage
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so for example 94 so 94 is a percentage
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which can be get
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for multiple students right so there
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might be a chance so that should not be
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considered as a percentage so coming to
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the student id so student id will be the
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unit
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right so
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no two students will share the same
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student id so such attribute we call it
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as a unique attribute and that is we
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call it as a primary key to identify the
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complete triple
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right
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and the next
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one data item
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so data item means the actual data so
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this is also called as
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cell data cell data so you can see this
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is one cell
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another cell another cell so these
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points we call it as a cells these
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blocks we call it as a cells so a cell
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is an intersection of a tuple and
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attribute okay a cell is an
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intersection
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intersection of
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a tuple
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and
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attribute
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so simply we can say it has intersection
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of row and column so if you observe this
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one it is an intersection of tuple and
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column right so horizontally horizontal
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row
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right and a vertical column so this will
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be represented as tuple and attribute
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intersection
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and these data must be
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okay this data must be atomic atomic
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means it should
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have a single value the data cell or
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data item should have a single value
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right for example student id so one not
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one comma one or two this is not a valid
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so it should have only one value so one
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not one so student name suddenly comma
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abc so it is not a valid because it
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should have only one value so the data
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the cell data or a data item should have
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a single value a single value
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right so
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relation
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triples attributes data item
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the next one
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the next terminology
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is a cardinality
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cardinality so here the cardinality
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means
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a number of
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tuples
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gives the cardinality so in this example
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how many tuples are there one two and
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three so the cardinality of a student
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table
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cardinality
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of
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student table
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is
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3 because we are having the 3 tuples 3
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rows so number of tuples or
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number of rows gives the cardinality
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okay the next one
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degree
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so degree means
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number of
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attributes
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number of attributes gives the degree so
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this is nothing but
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cardinality
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and
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this is nothing but
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degree right cardinality 3 a degree 3
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because number of attributes for the
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student table
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is in
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3
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so degree
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of
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student table
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three because student id student name in
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a person is three attributes are there
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that means the three columns right so
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the degree of a student table will be
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three cardinality
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it's a number of tuples or number of
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rows or number of records
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the next one is
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domain
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so domain means all the possible values
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given
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for an
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attribute
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so
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attribute is a column so we need we are
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supposed to give a value for the
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attribute right so
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the what are the possible values that
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should be given for an attribute is
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called a domain in this example consider
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this percentage so percentage will be
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0 to 100 in between 0 and 100 right so
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that is called a domain so here the
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domain
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for a percentage
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is
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0 to 100
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so this is called
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a domain right the possible values given
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for the
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attribute and the last one it say
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null values
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now values so coming to this null values
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if
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a cell
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kept blank
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during a data insertion
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then that particular cell will be given
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as a null values cell or attribute
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whatever it may be for example the
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student id 101 sandeep and if you are
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not i am not giving this percentage
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right i just kept blank then it will be
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filled with a
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null value so this is not equal to
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not equal to 0
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right so
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null the null means that doesn't it
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implies that the percentage is 0 right
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so that percentage cell has been left
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blank
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right so we can fill that percentage in
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future
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so at present that cell has been kept
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left
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okay so and null value means if any cell
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or an attribute kept blank during the
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data insertion
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that blank will be represented with a
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null that blank will be represented
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within null and this is not equal to 0
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or a space
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or any space
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right it's not equal to 0 or any space
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so this is the null values
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so i hope you understood the basic
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terminologies of our dbms so this is
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called a relation the table is called as
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a relation and the rows are called as a
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tuples or records and the columns we
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call it as a attributes and each
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attribute we have we should have the
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name and
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unique attribute should be represented
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with a primary key in order to represent
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the complete tuple and
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the number of tuples we call it as a
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cardinality the number of columns we
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call it as a degree
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and domain the possible values given for
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an attribute is called the mind
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and
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null values if the cell is kept blank
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during the data and session that
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particular cell will be filled with the
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null values and it should it doesn't
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mean it equal to zero or a space
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right so this is this is the
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basic introduction to rdbms and the
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basic terminologies used in the
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relational database management system
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right so hope you understood this one
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and if you are having any doubts
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regarding this one feel free to post
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your doubts in the comment section
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definitely i will try to clarify all
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your doubts
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you very much