Relational Database Operators

Relational Set Operators uses relational algebra to manipulate contents in a database. All together there are eight different types of operators. These operators are SQL commands. SELECT is the command to show all rows in a table. It can be used to select only specific data from the table that meets certain criteria. This command is also referred to as the Restrict command. UNION. It combines all of the rows in one table with all of the rows in another table except for the duplicate tuples. The tables are required to have the same attribute...

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Codd's Rule

Codd's Rule for Relational DBMS E.F Codd was a Computer Scientist who invented the Relational model for Database management. Based on relational model, the Relational database was created. Codd proposed 13 rules popularly known as Codd's 12 rules to test DBMS's concept against his relational model. Codd's rule actualy define what quality a DBMS requires in order to become a Relational Database Management System(RDBMS). Till now, there is hardly any commercial product that follows all the 13 Codd's rules. Even Oracle follows only eight and half(8.5)...

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Generalization and Specilization in ER Model

The Enhanced ER Model As the complexity of data increased in the late 1980s, it became more and more difficult to use the traditional ER Model for database modelling. Hence some improvements or enhancements were made to the existing ER Model to make it able to handle the complex applications better. Hence, as part of the Enhanced ER Model, along with other improvements, three new concepts were added to the existing ER Model, they were: Generalization Specialization Aggregration Generalization Generalization is a bottom-up approach in which...

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ER Diagram MODEL

Working with ER Diagrams ER Diagram is a visual representation of data that describes how data is related to each other. In ER Model, we disintegrate data into entities, attributes and setup relationships between entities, all this can be represented visually using the ER diagram. For example, in the below diagram, anyone can see and understand what the diagram wants to convey: Developer develops a website, whereas a Visitor visits a website...

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ER MODEL BASIC LEVEL

 DBMS ER Model Entity-relationship model is a model used for design and representation of relationships between data. The main data objects are termed as Entities, with their details defined as attributes, some of these attributes are important and are used to identity the entity, and different entities are related using relationships. In short, to understand about the ER Model, we must understand about: Entity and Entity Set What are Attributes? And Types of Attributes. Keys Relationships ER Model: Entity and Entity Set Considering...

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TEXTBOOK SOLUTION LESSON 1 INVOCATION

INVOCATION  TEXTBOOK SOLUTION LESSON 1 INVOCATION Translated from Atharvaveda STANZA FOR COMPREHENSION Let us have concord with our own people, And concord with people who are strangers to us Asvins, create between us and the strangers a unity of hearts. May we unite in our minds, unite in our purposes, and not fight against the divine spirit within us. Let not the battle-cry rise amidst many SIain, nor the arrows of the War-God fall with the break of the day. (M.P. 2015) Answer these questions: 1. Who is called to create unity of hearts...

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