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DBMS Database Models

DBMS database models

 

Data model: Data model shows how data is represented in the conceptual level of the database architecture

In the history of database design, 5 database models have been used

Flat file DBMS

  • The file management system was the first method used to store data in the computer is a database
  • Each data item is stored on a disc sequentially in one large file 
  • If you want to locate a particular item the search start from the beginning and each item is checked one by one sequentially till the match is found
    Drawbacks
    Data duplication, very poor security, retrieving of data is very slow, no support for data, types dynamic memory allocation, concurrent data sharing is not allowed, no security mechanism through passwords, etc
DBMS Database Models

Relational DBMS

  • It was first outlined by EF.codd 1970

The 2 components of the relational model are:

    1. collection of objects or relations that stores the data
    2. operations that can act on relations to produce other relations

This is the most frequent and commonly database today

Data integrity, logical representation in the form of table rows and columns, no data redundancy, logical links between relations are maintained, null, values integrity constraint, provides high security, unlimited size, security, range of data types, multiple users can work at a time

Hierarchical DBMS 

  • organize data like a tree structure, record types  are the same as a relational data model 
  • The hierarchical data model is implemented based on one too many relations between parent and child records
  • Because of a parent, child records in one-many relation  many child records have single parent records as a result of repetition  of child records occur

Network DBMS

  • in 1970s CODASY(conference on data system language) committee introduced a network data model 
  • in this data, the model will maintain less duplicate data  because their parent-child records are  implemented based on many-many  relation 
  • In this model also data is represented in the format of records and also record type is the same as a table in relation format

Object-relational DBMS

  • In this  model relational database but within object-oriented database design
  • Object, class, inheritance  is directly supported  In database schema and the query language
  • It provides a middle ground between the relational database and object-oriented database
  • are OOPS is added to the relational database design productivity, security boosts a lot