DBMS

What are the types of Database Architecture? DBMS Tutorial

Types of Database Architecture Understanding DBMS Architecture A Database Management system is not always directly available for users and applications to access and store data in it. A Database Management system can be centralised(all the data stored at one location), decentralised(multiple copies of database at different locations) or hierarchical, depending upon its architecture. 1-tier DBMS architecture also exist, this …

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What is Codd’s Rule In Database Management System?

E.F Codd was a Computer Scientist who invented Relational model for Database management. Based on relational model, Relation 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 …

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What is RDBMS Concepts in Database Management System?

A Relational Database management System(RDBMS) is a database management system based on relational model introduced by E.F Codd. In relational model, data is represented in terms of tuples(rows). RDBMS is used to manage Relational database. Relational database is a collection of organized set of tables from which data can be accessed easily. Relational Database is …

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What is Database Keys in DBMS?

Database Keys Keys are very important part of Relational database. They are used to establish and identify relation between tables. They also ensure that each record within a table can be uniquely identified by combination of one or more fields within a table. Super Key Super Key is defined as a set of attributes within …

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Normalization of Database

Normalization of Database Database Normalisation is a technique of organizing the data in the database. Normalization is a systematic approach of decomposing tables to eliminate data redundancy and undesirable characteristics like Insertion, Update and Deletion Anamolies. It is a multi-step process that puts data into tabular form by removing duplicated data from the relation tables. …

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What Is Structure Query Language(SQL) ?

Introduction to SQL Structure Query Language(SQL) is a programming language used for storing and managing data in RDBMS. SQL was the first commercial language introduced for E.F Codd’s Relational model. Today almost all RDBMS(MySql, Oracle, Infomix, Sybase, MS Access) uses SQL as the standard database language. SQL is used to perform all type of data …

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create command

create command create is a DDL command used to create a table or a database. Creating a Database To create a database in RDBMS, create command is uses. Following is the Syntax, create database database-name; Example for Creating Database create database Test; The above command will create a database named Test. Creating a Table create …

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alter command

alter command alter command is used for alteration of table structures. There are various uses of alter command, such as, to add a column to existing table to rename any existing column to change datatype of any column or to modify its size. alter is also used to drop a column. To Add Column to …

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Data Manipulation Language (DML)

DML command Data Manipulation Language (DML) statements are used for managing data in database. DML commands are not auto-committed. It means changes made by DML command are not permanent to database, it can be rolled back. 1) INSERT command Insert command is used to insert data into a table. Following is its general syntax, INSERT …

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All Transaction Control Language(TCL) commands

TCL command Transaction Control Language(TCL) commands are used to manage transactions in database.These are used to manage the changes made by DML statements. It also allows statements to be grouped together into logical transactions. Commit command Commit command is used to permanently save any transaaction into database. Following is Commit command’s syntax, commit; Rollback command …

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WHERE clause

Where clause is used to specify condition while retriving data from table. Where clause is used mostly withSelect, Update and Delete query. If condititon specified by where clause is true then only the result from table is returned. Syntax for WHERE clause SELECT column-name1, column-name2, column-name3, column-nameN from table-name WHERE [condition]; Example using WHERE clause …

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SELECT Query

Select query is used to retrieve data from a tables. It is the most used SQL query. We can retrieve complete tables, or partial by mentioning conditions using WHERE clause. Syntax of SELECT Query SELECT column-name1, column-name2, column-name3, column-nameN from table-name; Example for SELECT Query Conside the following Student table, S_id S_Name age address 101 …

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Like clause

Like clause is used as condition in SQL query. Like clause compares data with an expression using wildcard operators. It is used to find similar data from the table. Wildcard operators There are two wildcard operators that are used in like clause. Percent sign % : represents zero, one or more than one character. Underscore …

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Group By Clause

Group by clause is used to group the results of a SELECT query based on one or more columns. It is also used with SQL functions to group the result from one or more tables. Syntax for using Group by in a statement. SELECT column_name, function(column_name) FROM table_name WHERE condition GROUP BY column_name Example of …

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HAVING Clause In Dbms

having clause is used with SQL Queries to give more precise condition for a statement. It is used to mention condition in Group based SQL functions, just like WHERE clause. Syntax for having will be, select column_name, function(column_name) FROM table_name WHERE column_name condition GROUP BY column_name HAVING function(column_name) condition Example of HAVING Statement Consider the …

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