Database Articles - Page 65 of 546

SQL is a Structured Query Language which is the standard and most widely used programming language for relational databases. It is used to manage and organize data in all sorts of systems where all varieties of data relationships exist.Structured Query Language (SQL) ClausesThe SQL clauses are of three types as shown below−Let us learn about them one by one.GROUP BY CLAUSESQL GROUP BY is used to arrange identical data into groups. It is used with the SQL SELECT statement. The GROUP BY statement follows the WHERE clause in a SELECT statement and precedes the ORDER BY clause. It is also ... Read More

A nested query is a query that has another query embedded within it. The embedded query is called a subquery.A subquery typically appears within the WHERE clause of a query. It can sometimes appear in the FROM clause or HAVING clause.ExampleLet’s learn about nested queries with the help of an example.Find the names of employee who have regno=103The query is as follows −select E.ename from employee E where E.eid IN (select S.eid from salary S where S.regno=103);Student tableThe student table is created as follows −create table student(id number(10), name varchar2(20), classID number(10), marks varchar2(20)); Insert into student values(1, 'pinky', 3, ... Read More

Let us understand what table, view and synonym in the structured query language (SQL) are.Table, view and synonymA table is a repository of data, where in the table it is a physical entity. A table resides physically in the database.A view is not a part of the database’s physical representation. It is precompiled, so that data retrieval behaves faster and also provides a secure accessibility mechanism.A synonym is an alternate name assigned to a table, view, sequence or program unit.ExampleCreate table employee (empID integer primary key, name varchar2(30), skill varchar2(30), salary number(20), DOB datetime).Let’s say there is a scenario where ... Read More

The overall design of the Database Management System (DBMS) depends on its architecture. A large amount of data on web servers, Personal Computers (PC) and other elements are linked with networks with the help of basic client or server architecture.PCs and workstations are part of Client architecture that are connected over the network. The architecture of DBMS depends on how the users are linked to the database.There are three kinds of DBMS Architecture, which are as follows −Tier-1 Architecture.Tier-2 Architecture.Tier-3 Architecture.Tier-3 ArchitectureThe 3-tier architecture contains one more layer between the client and the server.In this architecture, there is no direct ... Read More

The overall design of the Database Management System (DBMS) depends on its architecture. A large amount of data on web servers, Personal Computers (PC) and other elements are linked with networks with the help of basic client or server architecture.PCs and workstations are part of Client architecture that are connected over the network. The architecture of DBMS depends on how the users are linked to the database.There are three kinds of DBMS Architecture, which are as follows −Tier-1 Architecture.Tier-2 Architecture.Tier-3 Architecture.Tier-2 ArchitectureThe 2-tier Architecture is based on a client-server machine.In this type of architecture, the applications on client-side interact directly ... Read More

The overall design of the Database Management System (DBMS) depends on its architecture. A large amount of data on web servers, Personal Computers (PC) and other elements are linked with networks with the help of basic client or server architecture.PCs and workstations are part of Client architecture that are connected over the network. The architecture of DBMS depends on how the users are linked to the database.There are three kinds of DBMS Architecture, which are as follows −Tier-1 Architecture.Tier-2 Architecture.Tier-3 Architecture.Tier is a physical unit where the program code or a process is run.For example − data base server, application ... Read More

The Database Management System (DBMS) is defined as a software system that allows the user to define, create and maintain the database and provide control access to the data.It is a collection of programs used for managing data and simultaneously it supports different types of users to create, manage, retrieve, update and store information.Applications of DBMSIn so many fields, we will use a database management system.Let’s see some of the applications where database management system uses −Railway Reservation System − The railway reservation system database plays a very important role by keeping record of ticket booking, train’s departure time and ... Read More

Hardware, Software, Data, Database Access Language, Procedures and Users all together form the components of a DBMS.Let us discuss the components one by one clearly.HardwareThe hardware is the actual computer system used for keeping and accessing the database. The conventional DBMS hardware consists of secondary storage devices such as hard disks. Databases run on the range of machines from micro computers to mainframes.SoftwareSoftware is the actual DBMS between the physical database and the users of the system. All the requests from the user for accessing the database are handled by DBMS.DataIt is an important component of the database management system. ... Read More

There are so many characteristics of a database management system, which are as follows − A database management system is able to store any kind of data in a database. The database management system has to support ACID (atomicity, consistency, isolation, durability) properties. The Database management system allows so many users to access databases at the same time. Backup and recovery are ... Read More

The Database Management System (DBMS) is defined as a software system that allows the user to define, create and maintain the database and provide control access to the data.It is a collection of programs used for managing data and simultaneously it supports different types of users to create, manage, retrieve, update and store information.PurposeThe purpose of DBMS is to transform the following −Data into information.Information into knowledge.Knowledge to the action.The diagram given below explains the process as to how the transformation of data to information to knowledge to action happens respectively in the DBMS −Previously, the database applications were built ... Read More