Tuesday, January 6, 2015

Data Manipulation Language (DML)

What is DML? / List of operations that can be performed by Data Manipulation Language / DML examples / Types of DML / Procedural and Declarative DML




Data Manipulation Language (DML)


Data Manipulation is about handling the data stored in a database differently. The following operations would be considered as data manipulation in a database;

  • Retrieving the data stored in the database – the way to view the data stored in the database

  • Insertion of new data into the database – the way to insert and store the data in the database

  • Deletion of stored data – the way to delete old or unwanted data from the database

  • Modification of the stored data – the way to modify when required or when false data stored

The above said operations can be executed in Oracle using the following SQL statements respectively, for example;

Assume a table Teacher with attributes TID, Name, and Phone number. 

RetrievalSELECT * FROM Teacher;
InsertionINSERT INTO Teacher VALUES (100, ‘Ramesh’, 9900887771);
DeletionDELETE FROM Teacher WHERE TID = 100;
ModificationUPDATE Teacher SET phone = 9900887766;



There are basically two types of DML languages;
1. Procedural DMLs – in procedural DMLs the user has to specify

  • how to get the required data along with

  • what data are required.

2. Declarative DMLs (Non-procedural) – it requires the user to specify

  • What data are required only. (Note:- The DML component of Structured Query Language (SQL) is declarative, ie., non-procedural)
 
************************
Related links:

No comments:

Post a Comment

Featured Content

Multiple choice questions in Natural Language Processing Home

MCQ in Natural Language Processing, Quiz questions with answers in NLP, Top interview questions in NLP with answers Multiple Choice Que...

All time most popular contents

data recovery