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A database management system (DBMS) is system software for creating and managing databases. The DBMS provides users and programmers with a systematic way to create, retrieve, update and manage data
Typology: Lecture notes
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◦ Entities ◦ Attributes ◦ Relationships
◦ Standard Symbols to use ◦ Chen Notation
◦ An entity that exists independently of other entity types
◦ An entity types whose existence depends on some other entity ◦ This is depended on the scenario (interaction with other entities) ◦ I.e :- A call cannot exist without phone (phone number)
Simple attribute / Single-value attribute An attribute that cannot be broken down into smaller components Composite attribute An attribute that can be broken down into component parts Derived attribute An attribute whose values can be calculated from related attribute values
Multi-value attribute An attribute that may take on more than one value for a given entity instance (I.e ;_ phone number) Key Attribute Uniquely identifiers individual instances of an entity type Can be single attribute or combination of attributes that uniquely identifies individual instances of an entity type
Some Examples
Some Examples