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[Music]
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hello friends welcome back to our
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channel so in today's session we will
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discuss about one more topic in dbms
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that is a er model
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so what is this air model
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so er stands for
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entity relationship model
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so in the previous sessions we have
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discussed about what is an entity and
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what is the relationship and what are
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the different types of relationships
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right so
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this er model is a
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pictorial representation
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a pictorial representation
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of
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database
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of database
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showing
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entity types
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entity types
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and
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their relationships
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are they
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relationships
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right so
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identifying the entity types and the
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relation between the entity types and
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completely representing that in a
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diagrammatic format is called the er
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model
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right entity relationship model
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now what are the components of this
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particular er model
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components
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components of ear
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the first one
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entity
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entity
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attributes
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attribute
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relationship
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relationship so these three are the
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major components of any er diagram
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so we have studied about these entities
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what is a strong entity
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another one is a weak entity
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weak entity
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coming to the attitudes we have seen
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simple attribute
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composite
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key attribute
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single value
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multivalued
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multi-valued
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and relationships we have seen in the
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previous session that there is a
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one-to-one
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one-two-one relationship
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one-to-many relationship
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many too many relationships
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mini to many relationship
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so these are the major components of any
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er diagram
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any er diagram right so first we need to
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identify the entities and then we need
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to identify the attributes for every
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entity there will be different
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attributes so we need to identify the
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attributes and then we have to identify
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the relationship among the different
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entities because this is a rdbms there
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should be a relation between two
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different tables so that relation should
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be defined with the help of this
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relationship
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right and for everything
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as i said that er diagram or er model is
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a high level representation and it is a
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diagrammatic representation of a
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database so we there there are different
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notations for each and every
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entity or attribute or relationship
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right so hope you understood this basic
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introduction about the er model what is
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a er model and
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what are the components of er model or
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air diagram
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right so i will stop here in the next
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section we will see the notations what
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are the different notations for these so
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how to identify the strong entity i mean
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how to represent the strong entity using
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a diagram how to represent the weak
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entity using a diagram how to represent
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the attributes of an entities and how to
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represent the relationships
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right so everything we will see in the
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next session so
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let's stop here and if you are having
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any doubts regarding this one feel free
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to post your notes in the comment
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section definitely i'll try to clarify
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all your doubts if you really enjoyed my
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