Relational Databases - Database Management System
Subject and UNIT: Database Management System: Unit I: Relational Databases
There are two formal query languages associated with relational model and those are relational algebra and relational calculus.
Relational Databases - Database Management System
Subject and UNIT: Database Management System: Unit I: Relational Databases
The foreign key is a key in one table that refers to the primary key of another table. The foreign key is basically used to link two tables.
Relational Databases - Database Management System
Subject and UNIT: Database Management System: Unit I: Relational Databases
Database integrity means correctness or accuracy of data in the database. A database may have number of integrity constraints.
Relational Databases - Database Management System
Subject and UNIT: Database Management System: Unit I: Relational Databases
Keys are used to specify the tuples distinctly in the given relation. Various types of keys used in relational model are - Superkey, Candidate Keys, primary keys, foreign keys.
Relational Databases - Database Management System
Subject and UNIT: Database Management System: Unit I: Relational Databases
In relational model, table is a collection of data items arranged in rows and columns. The table cannot have duplicate data or rows. Below is an example of student table
Relational Databases - Database Management System
Subject and UNIT: Database Management System: Unit I: Relational Databases
Relation database is a collection of tables having unique names. For example - Consider the example of Student table in which the information about the student is stored.
Relational Databases - Database Management System
Subject and UNIT: Database Management System: Unit I: Relational Databases
Definition: Database schema is a collection of database objects like tables, views, indexes and so on associated with one particular database username. This username is called the schema owner.
Relational Databases - Database Management System
Subject and UNIT: Database Management System: Unit I: Relational Databases
Data independence is an ability by which one can change the data at one level without affecting the data at another level. Here level can be physical, conceptual or external.
Relational Databases - Database Management System
Subject and UNIT: Database Management System: Unit I: Relational Databases
The typical structure of typical DBMS is based on relational data model .The lowest part of the architecture is for disk storage.
Relational Databases - Database Management System
Subject and UNIT: Database Management System: Unit I: Relational Databases
Definition: It is a collection of conceptual tools for describing data, relationships among data, semantics (meaning) of data and constraints.
Relational Databases - Database Management System
Subject and UNIT: Database Management System: Unit I: Relational Databases
Database is a collection of interrelated data and set of programs that allow users to access or modify the data.
Relational Databases - Database Management System
Subject and UNIT: Database Management System: Unit I: Relational Databases
Earlier database systems are created in response to manage the commercial data. These data is typically stored in files.