DBMS is a subject related to storage and retrieval of data from physical media.

The Three Schema Architechture of Relational database

The Relational Database Management Systems is the most popular database system. The overall structure of the Database System is given here. The relational database is at three level or three schemas. Internal level with internal schema In this level, an internal schema is defined and it is more related to the physical storage and access … Read more

How to Add a Constraint and Remove a Constraint From a Relation?

Constraints are like rules in relation so that you cannot violate them. There are plenty of constraint types that we use. In this article, we will add a check constraint and delete it from a relation. The general process to add or remove a constraint from a Relation is as follows. STEP 1: In this … Read more

Understanding GROUP BY and HAVING Clause

We use SELECT-FROM-WHERE kind of statement to run queries that get us specific rows from a relation. In the select statement, WHERE is the condition that returns specific rows from a relation. What if we want to group the information? The GROUP BY and HAVING clause helps you to group the resultant rows by a … Read more

JOIN Concepts in Relational Database Management System

JOIN put condition (selections and projections) on a CROSS-PRODUCT from two or more tables and the result is a smaller relation than the CROSS-PRODUCT In DBMS, JOIN is an important operation in relational algebra and it extracts useful information from joining two or more relations. In this lab, you will create two tables TEACHER and … Read more

Converting an E-R Model into Relational Model in DBMS

In this lesson you will learn to convert er model into relational model. First step in designing a database is to create an entity-relationship model. Then the entity-relationship model is converted into a relational model. The relational model is nothing but a group of tables or relations that create for your database. Read: DBMS BasicsRead: … Read more

Understanding Basic SQL Queries in DBMS

Data Manipulation Language ( DML ) is the language used to maintain the database in a DMBS. The SQL (Structured Query Language) is the most popular language to manipulate databases. DML Commands The DML commands perform following tasks on a database. INSERT SELECT DELETE UPDATE The SQL being a DML can do above task without … Read more

Basic Data Definition Language(DDL) Commands

The Data Definition Language( DDL ) commands are used for creating new or modify existing schema of a relation. You can also set constraints such as key constraints, foreign key constraints, etc on a relation. CREATE TABLE Command This command creates a new relation or table. You must specify the fields and data type for … Read more

Normalization in DBMS

Designing a database structure without proper planning would cause duplicate data and problem updating the database. This will result in an inconsistent database. The process of normalization is to make an efficient database design that allow faster and efficient access while maintaining the accuracy. What is Normalization? Normalization is a database design technique that cuts … Read more

Locks in Database Management

Previously, you learned about the concurrency mechanism in database. You know that the concurrency is maintained in a serialized manner, giving the impression that there is indeed some concurrency. The locking technique has to do a lot with this achievement of efficient access to database. What is a Lock? A lock is a variable associated … Read more

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