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An overview of database systems, focusing on entities, attributes, records, and the relational and hierarchical models. It covers the concepts of data independence, metadata, data encoding, data control and protection, and various data models. The text also discusses the advantages and disadvantages of hierarchical and network models.
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EMPLOYEE ID
EMPLOYEE NAME
EMPLOYEE ID
EMPLOYEE.NAME
EMPLOYEE ID
EMPLOYEE NAME
A) ONE TO ONEONE TO ONE
EMPLOYEE ID EMPLOYEE SALARY SALARY EMPLOYEE ID EMPLOYEE ID SALARY
B) ONE TO MANYONE TO MANY
(MANY TO ONE RLTN BTW EMPLOYEE ID & SALARY)
RELATIONSHIP AMONG ENTITIES RELATIONSHIP EXIST AMONG DIFF ENTITIES EVEN THOUGH RELATIONSHIP MAY INVOLVE MORE THAN TWO ENTITIES - WE WILL CONCENTRATE ON THE RELATIONSHIP BTW TWO ENTITIES
STUDENTS ENROL COURSE LMNT
ENTITY SETS RELATIONSHIP
BORROWER
BORROWER
CUSTOMER LOAN
CUSTOMER LOAN
ONE TO MANY
REPORTS TO
EMPLOYEE
BINARY RELATIONSHIP INVOLVING SAME ENTITY