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Closure Of Functional Dependency Introduction The Closure Of Functional Dependency means the complete set of all possible attributes that can be functionally derived from given functional dependency using the inference rules known as Armstrong’s Rules. If “F” is a functional dependency then closure of functional dependency can be denoted using “{F}+”. There are three steps to calculate closure of functional dependency.  These are Step-1 : Add the attributes which are present on Left Hand Side in the original functional dependency.       Step-2 : Now, add the attributes present on the Right Hand Side of the functional dependency.       Step-3 : With the help of attributes present on Right Hand Side, check the other attributes that can be derived from the other given functional dependencies.       Repeat this process until all the possible attributes which can be derived are added in the closure. Closure Of Functional Dependency Examples E...

The commercial database system requires a more user friendly query language . SQL i.e. structured query language ,it uses a combination of relational algebra and relational calculus constructs. The user can write SQL statement and submit it to the database. DBMS will retrieve the appropriate data from disk and return it to user. Basic structure:- The SQL expression consists of 3 clauses or components. Select<list of attributes> From<table name> Where<condition>; Parts of SQL DDL Commands Create Table Drop Table Alter Table DML Commands Insert Update Delete A relational database consists of multiple related tables. A table consists of rows and columns. Tables allow you to store structured data like customers, products, employees, etc. To create a new table, you use the CREATE TABLE statement. The following illustrates the basic syntax of the CREATE TABLE statement: CREATE TABLE [IF NOT EXISTS] table_name ( column1 datatype(length) column_contraint, ...

ER Model An Entity–relationship model (ER model) describes the structure of a database with the help of a diagram, which is known as Entity Relationship Diagram (ER Diagram). An ER model is a design or blueprint of a database that can later be implemented as a database. The main components of E-R model are: entity set and relationship set. What is an Entity Relationship Diagram (ER Diagram)? An ER diagram shows the relationship among entity sets. An entity set is a group of similar entities and these entities can have attributes. In terms of DBMS, an entity is a table or attribute of a table in database, so by showing relationship among tables and their attributes, ER diagram shows the complete logical structure of a database. Lets have a look at a simple ER diagram to understand this concept. Here are the geometric shapes and their meaning in an E-R Diagram.  We will discuss these terms in detail in the next section(Components of a ER Diagram) of this guide so don’t worry too much...

Introduction to DBMS In typical business environment, it is always essential to be able to produce the right information at the right time with minimum efforts. The database shows a change in storage, access and management of data. A DBMS (Database Management System) is a complex software system that is used to manage, store and manipulate data in the database. It is utilized by a large variety of users, to retrieve and manipulate data under its control. The users could be utilizing that database concurrently from on-line terminals and/or in a batch environment via application programs written in a high-level language. Data and Information Data can be defined as a representation of facts, concepts or instructions. Information is organized or classified data so that it has some meaningful values. Information is the processed data on which few decisions or actions can be taken. The processed data must have the following characteristics: Timely: Information should ...

Introduction to file system File File is a collection of records which are logically related to any object. Record value can in any form like data.  For eg. : Each students records which having values of Roll no, Name, Class. For arranging data we use file. For eg.: files of bank‟s customer, files of department, files of stack records etc.  Files are recorded on secondary storage such as magnetic disks, magnetic tables and optical disks. Types of file  Physical file Physical file concern with actual data that is stored.  It stores description about how the data is to be represented.  Logical file Logical file: do not contain data.  They contain a description of records that are found in one or more physical files.  A logical file is a view or representation of one or more physical files.  Special character file At the time of file creation we insert some special characters in file. For eg: Control + z for end of a file which having ASCII value 26 ...