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DBMS basics
- 1. PRANVEER SINGH INSTITUTE OF TECHNOLOGY NH-2 BHAUTI, KANPUR PROFESSIONAL COMMUNICATION PROJECT WORK Presentation by:- Under Guidance of Praveen Srivastava Mrs. Raavee Tripathi CS - 1 A Roll No:1116410111 1
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- 3. 3 CONTENTS INTRODUCTION PURPOSE OF DBMS DATABASE ABSTRACTION DATA MODELS THE RELATIONAL MODEL COMPARISIONOF DATA MODELS
- 4. 4 INTRODUCTION A database may be defined as a collection of interrelated data stored together to serve multiple applications A database system is basically a computer based record keeping system. The collection of data, usually referred to ac the database, contains information about one particular enterprise. It maintains any information that may be necessary to the decision-making processes involved in the management of that organization.
- 5. 5 Purpose of DBMS • Database reduce the data redundancy to a large extent. • Databases can control data inconsistency to a large extent. • Database facilitate sharing of data. • Database enforce standards. • Database can ensure data security. • Integrity can be maintained through database.
- 6. 6 DATABASE ABSTRACTION • Levels of Database Implementation. 1. Internal Level 2 . Conceptual Level 3 . External Level • Data Independency. The ability to modify a scheme definition in one level without affecting a scheme definition in the next higher level is called Data independency.
- 7. 7 DATA MODELS • The Relational Data Model. In relational data model, the data is organized into tables {i.e., rows $ column} • The Network Data Model. In network model, data is represented by collections of record $ relationships among data are represented by links. • The Hierarchical Data Model. The only difference between hierarchical $ relational data model is that, records are organized as trees rather than arbitrary graph.
- 8. 8 THE RELATIONAL MODEL 1. Terminology • Relation : It is a table i.e., data is arranged in rows and columns. • Domain : It is a pool of values from which the actual values appearing in a given column are drawn. • Tuple : The rows of tables (relation) are generally referred to as Tuple. • Attribute : The columns of a table (relation) are generally referred to as attribute. • Degree : The number of attributes in a relation. • Cardinality : The number of tuples in a relation.
- 9. 9 2. VIEWS A view is a (virtual) table that does not really exist in its own right but is instead derived from one or more underlying base table(s). 3. Structure of Relational Databases • Keys a)Primary key: It is a set of one or more attributes that can uniquely identify tuples within the relation. b)Canditate key: All attribute combinations inside a relation that can serve as primary key are candidate keys as they are candidates for the primary key position.
- 10. 10 c) Alternate key : A candidate key that is not the primary key is called an alternate key. d) Foreign key : A non-key attribute, whose values are derived from the primary key of some other table, is known as foreign-key in its current table. • Referential integrity It is a system of rules that a DBMS uses to ensure that relationships between records in related tables are valid, and that users don’t accidentally delete or change related data.
- 11. 11 Comparison of Data Models Data models can be evaluated on the basis of usability, implementability and performance. Data experts have been debating for some time which DBMS data model is ‘best’. The answer depends, in part, on philosophical orientation. The hierarchical model is the oldest model and has long been the most popular on mainframes. People who think the user should be able to have some control over the details of storage allocation and search paths often prefer network systems. However, few database systems are fully relational. Instead they graft relational features on a basic hierarchical or network structure.
- 12. 12 Information plays an important role in management of the building systems and the DBMS is providing information and updates and supplies relevant multi-user information to the concerned users. Based on the statistics the DBMS will provide, through out the year major planning could be done and that could lead deriving parameters for AI Techniques and fuzzy logic which could make the building system more efficient and responsive to the human needs and comfort.
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