Utsav Mahendra : Introduction to Database and managemnet
INTRODUCTIONDATABASE DESIGN AND MANAGEMENT MADE BY : UTSAV MAHENDRA BBA 4502/09 AKSHAY KALRA BBA 4514/09
Database Management System• Database Management System is a collection of interrelated data and a set of programs to access those data.• Primary Goal of DBMS- provide a way to store and retrieve database.• Management of data involves both defining structure for storage of information and proving mechanisms for the manipulation of information.
Database System Applications• Banking• Airlines• Universities• Credit card transactions• Telecommunications• Finance• Sales• Manufacturing• Human resources
File System• File processing system is supported by a conventional operating system.• This System stores permanent records in various files and it needs different application programs to extract and Add records.• Keeping Organizational information in a file- processing system has number of major disadvantages.
Disadvantages of File System• Data Redundancy and Inconsistency• Difficulty in accessing data• Data isolation• Integrity problems• Security problems
View of Data1. Data Abstraction2. Instances3. Schema
Data Abstraction• For the system to be usable ,it must retrieve data efficiency.• The need for efficiency has led designers to use complex data structures to represent data in the database.• Since many database system users are not computer trained, developers hide the complexity from users through several levels of abstractions.
Levels of Abstraction1. Physical Level : The lowest level of abstraction describes how the data are actually stored.2. Logical Level : The next – higher level of abstraction describes what data to be stored in database.3. View Level : The highest level of abstraction describes only a part of the entire database.
Instances and Schemas• Database changes over time as information is inserted and deleted. The Collection of information stored in the database at a particular moment is called Instance of database .• The overall design of the database is called the database Schema .Schemas are changed infrequently.
• Database system have several schemas partitioned according to the levels of abstraction.• Physical schema describes the database design at physical level• Logical schema describes the database design at the logical level.• Database may have several schemas at view level, sometimes called Subschemas, that describes different views of database.
Data Models• Structure of Database is the Data Model.• A Collection of Conceptual tools for describing Data, Data Relationships, Data Semantics and consistency constraints.The Concept of Data Model has 2 sections1.The Entity Relationship Model2.The Relational Model
The Entity Relationship Model• The Entity Relationship Model ( E.R Model ) is based on the perception of a real world that consists of a collection of basic objects called Entities.• An Entity is a thing or Object in the real world what is distinguishable from other objects.• For example each person is an Entity and bank Accounts can be considered as Entities.• Entities are described in the database by set of attributes.
• A relationship is an association among several Entities. Eg:Rectangle which represent Entity Sets.Eclipses which represent Attributes.Diamonds which represent Relationship among Entity sets.Lines which link attributes to Entity Sets and Entity Sets relationships
Relational Model• The Relational Model uses a collection of tables to represent both data and the relationships among those data.• Each table has Multiple Columns, Each Columns has a Unique name.• The Relational Model is an Example or Record Based Model.• Record Based Model is the database structured in fixed formats records of several types.
• Each table contains records of a particular type each record type defines a fixed number of files or attributes.• The Relational model is at the lower level of Abstraction than the ER Model and then translated to the Relational Model
Other Data Model• The Object Oriented Data Model is another data model that has seen increasing attention.• The Object Oriented Model can be seen as Extending of the ER Model with notions of Encapsulation, Methods and Object identity.• The Object relational Data Model combines features of the Object Oriented Data Model and Relational Data Model.
Data Base Language• A Database system provides a data definition language to specify the database schedule and a data Manipulation languages to Express database queries and updates.Data Definition Language• A Database schema by set of definitions Expressed by a special language called Data Definition Language.
Data Manipulation Language• Retrieval of Information stored in Database.• Insertion of New Information in Database.• Decision of Information from Database.• Modification of Information stored in Database.• Enables User to access or Manipulate data as organized by Appropriate Data Model.
Procedural Dml• Requires user to specify what data and how to get data.Declarative Dml• Requires user to specify what data are needed without specifying how to get the data.
Database Access for Application Programs• Application programs used to interact with database application programs written in C,C++,Cobol or Java.• By Providing an application programs can be used to send DML and DDL statements.• By Extending the Host Language syntax to embed DML calls
Database Users and User Interfaces• There are 4 different types of databases system users :• Navie Users are unsophisticated users who interact with the system invoking one of the application programs that have been written previously.• Application programmers are computer professionals who write application programs• Sophisticated users interact with the systems without writing programs.• Specialized users are sophisticated users who write the specialized database applications that do not fit into the traditional data processing framework.
Database Administrator• Main reason fro using DBMS is to have central control of both the data an the programs that access those data.• Functions of DBA• Schema Definition• Storage Structure and Access method Definition• Schema and physical organization Modification• Routine Maintenance