DBMS By Narinder Singh Computer Sc. Deptt

Topics What is DBMS What is DBMS File System Approach: its limitations File System Approach: its limitations Why we need DBMS? Why we need DBMS? Difference between DBMS and Programming Languages Difference between DBMS and Programming Languages Difference between DBMS and RDBMS Difference between DBMS and RDBMS Data Independence Data Independence

DBMS Database is collection of related Files. Database is collection of related Files. Database is organizing data into tabular form i.e. in the form of rows and columns. Database is organizing data into tabular form i.e. in the form of rows and columns. A Database Management System (DBMS) is a set of computer programs that controls the creation, maintenance, and the use of a database. A Database Management System (DBMS) is a set of computer programs that controls the creation, maintenance, and the use of a database. It allows organizations to place control of database development by database administrators (DBAs) and other specialists. It allows organizations to place control of database development by database administrators (DBAs) and other specialists. A DBMS is a system software package that helps the use of integrated collection of data records and files. A DBMS is a system software package that helps the use of integrated collection of data records and files. It allows different user application programs to easily access the same database. It allows different user application programs to easily access the same database.

File System Approach Storing the data into a single file that is not linking with other file is the traditional file system approach. Storing the data into a single file that is not linking with other file is the traditional file system approach. All the records resides in a single file leads to the problems such as data redundancy, inconsistency etc. All the records resides in a single file leads to the problems such as data redundancy, inconsistency etc.

Limitations of File System Approach Separation and isolation of data -Difficult to access data that is available (eg. from two files – Student that achieved good academic result and active in extra curriculum activities) Separation and isolation of data -Difficult to access data that is available (eg. from two files – Student that achieved good academic result and active in extra curriculum activities) Duplication of data -Cost time and money to enter data more than once -Additional storage space is needed - cost -Inconsistencies of data Duplication of data -Cost time and money to enter data more than once -Additional storage space is needed - cost -Inconsistencies of data Data dependence -File structure is defined in the program code. -Changes to an existing structure are difficult to make Data dependence -File structure is defined in the program code. -Changes to an existing structure are difficult to make Incompatible file formats -Programs are written in different languages, and so cannot easily access each other’s files. Incompatible file formats -Programs are written in different languages, and so cannot easily access each other’s files. Fixed Queries/Proliferation of application programs -Programs are written to satisfy particular functions. -Any new requirement needs a new program. Fixed Queries/Proliferation of application programs -Programs are written to satisfy particular functions. -Any new requirement needs a new program.

Advantages of DBMS  Controlling redundancy  Providing storage structure for efficient query processing.  Restricting unauthorized users.  Providing concurrency.  Providing backup and recovery.  Enforcing integrity constraints.  Improved data sharing.

Disadvantages of RBMS Centralization: That is use of the same program at a time by many user sometimes lead to loss of some data. Centralization: That is use of the same program at a time by many user sometimes lead to loss of some data. High cost of software. High cost of software. Technical expertise are required. Technical expertise are required.

DBA Database Administrator (DBA) is the person(s), who manages the database. Database Administrator (DBA) is the person(s), who manages the database. Functions of DBA includes Functions of DBA includes 1. Creation of database. 2. Decide Storage for the database. 3. Responsible for backup and recovery. 4. Create new users and assign privileges to them.

DBMS vs RDBMS DBMS has to be persistent, that is it should be accessible when the program created the data. A DBMS also has to provide some uniform methods independent of a specific application for accessing the information that is stored. DBMS has to be persistent, that is it should be accessible when the program created the data. A DBMS also has to provide some uniform methods independent of a specific application for accessing the information that is stored. Does not implements OOPs concepts. Does not implements OOPs concepts. RDBMS (Relational Data Base Management System) adds the additional condition that the system supports a tabular structure for the data, with enforced relationships between the tables. RDBMS (Relational Data Base Management System) adds the additional condition that the system supports a tabular structure for the data, with enforced relationships between the tables. Implements OOPs concepts Implements OOPs concepts

Data Independence Data Independence refers to the immunity of user applications to make changes in the definition and organization of data. Data Independence refers to the immunity of user applications to make changes in the definition and organization of data. The data independence and operation independence together gives the feature of data abstraction. There are two levels of data independence The data independence and operation independence together gives the feature of data abstraction. There are two levels of data independence a) Logical / Conceptual data independence. b) Physical data independence

 Logical data independence states that if changes are done in application software and physical structure of database changes need not to be done in conceptual structure.  Physical data independence states that if changes are done in application software and logical structure of database changes need not to be done in physical structure.