The Entity-Relationship Model
The Entity-Relationship (ER) model was originally proposed by Peter in 1976 as a way to unify the network and relational
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Types of Database System
Several criteria are normally used to classify DBMSs. The first is the data model on which the DBMS is based.
Read moreDBMS Architecture and Data Independence
Three important characteristics of the database approach are (1) insulation of programs and data (program-data and program-operation independence); (2) support
Read moreData Dictionary
We can define a data dictionary as a DBMS component that stores the definition of data characteristics and relationships. You
Read moreDatabase Languages
A database system provides a data definition language to specify the database schema and a data manipulation language to express
Read moreData Models
Underlying the structure of a database is the data model: a collection of conceptual tools for describing data, data relationships,
Read moreInstances and Schemas
Databases change over time as information is inserted and deleted. The collection of information stored in the database at a
Read moreDisadvantages of a DBMS
Danger of a Overkill: For small and simple applications for single users a database system is often not advisable. Complexity:
Read moreAdvantages and of a DBMS
Using a DBMS to manage data has many advantages: Data independence: Application programs should be as independent as possible from
Read moreCharacteristics of Database
The database approach has some very characteristic features which are discussed in detail below: Concurrent Use A database system allows
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