DBMS

• 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.

 DATABASE MODELS ARE

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

HIERARCHICAL 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".

NETWORK DATABASE MODEL:

• 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