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ER Diagrams to Table

REDUCING E-R DIAGRAM TO TABLE - A database which conforms to an E R diagram can be represented by collection of tables .For each entity set and for each relationship set in the database, we will create unique tables, which is assigned the name of the corresponding entity set or relationship sets . Each table has a no. of columns which have unique names. Each row in the table corresponds to an entity or a relationship.

REPRESENTATION OF STRONG ENTITY SET -Let E be a strong entity set with descriptive attributes a1, a2....aN . We represent this entity by table called E with N distinct columns, each of which corresponds to one of the attributes of E.

REPRESENTATION OF RELATIONSHIP SET - Let R be a relation ship set involving entity set E1,E2....En Let attribute(R) consists of 'm' attributes We can represent this relation ship set by a table called R with m distinct columns, each of which corresponds to one of the attributes in attribute (R) plus the primary key of E1..En.

REPRESENTION OF WEAK ENTITY SETS - Let A be a weak entity sets with attributes a1, a2, a3....aN. Let B be the strong entity set on which A is existence dependant. Let the primary key of B consists of the attributes b1,b2,b3...bk. We represent the entity set A by a table with one column each for attribute of the set {a1,a2,a3, ....aN} U { b1,b2,b3..bk}

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