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  • dbms are software which helps in organizing, controlling and using the data.
  • applications access the dams, which accesses the data.
  • dbms help us do various operations on the files, such as:
    • adding new files to database,
    • deleting existing files from database,
    • inserting data in existing files,
    • modifying data in existing files,
    • deleting data in existing files, and
    • retrieving or querying data from existing files.
  • examples are oracle, my sql, sql servers and db2 etc.



ADVANTAGES OF A DBMS:                                                                                                                                                                                                                                                                                                  MAJOR ADVANTAGES OF DBMS ARE GIVEN AS FOLLOWS:


  • PERMITTING DATA SHARING: Information can be shared to different users at the same time.
  • MINIMIZING DATA REDUNDANCY: Duplication of information or redundancy is reduced i.e.; same data is not stored again & again resulting in reduction of cost of storing information.
  • INTEGRITY CAN BE MAINTAINED: It ensures integrity of data as updates and changes are to be made at one place only. no need to change/ update data at several places which could result in mistakes.
  • IMPROVED SECURITY: Multiple users can access the same data which could be a risk also, if not controlled. through the use of passwords, access can be restricted to authorized user only.
  • PROGRAM AND FILE CONSISTENCY: File formats are standardized. this makes it easier to manage & maintain data when multiple programmers are involved.
  • PROGRAM/DATA INDEPENDENCE: When using dbms data does not reside in applications but in data bases, program & data are independent of each other.
  • USER-FRIENDLY: Dbms makes data access and manipulation easier. users need not depend on computer experts to meet their needs.
  • FASTER APPLICATION DEVELOPMENT: With dbms, application development becomes fast. since developer has to focus only on presentation of data rather than storage & retrieval.


 Disadvantages of a DBMS

  • COST: Implementing a dbms system can be expensive and time-consuming. training requirements alone can be quite costly.
  • SECURITY: Even with safeguards in place, it may be possible for some unauthorized users to access the database.


  • hierarchical database model,
  • network database model,
  • relational database model, and
  • object oriented database model


  • records are logically organized into a hierarchy of relationships.
  • an inverted tree patterns.
  • each record is related to the others in a parent-child relationship.
  • it has one-to-one and one-to-many relationships.
  • the top parent record in the hierarchy is called the root record.
  • all data searches must originate at the top or "root".


  • variation on the hierarchical model
  • in network model branches can be connected to multiple parents.
  • the network model permits a record to be a member of more than one parent at a time.
  • many-to-many relationships are possible.
  • the model, then, is more consistent with real-world business relationships

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