Download DATA DEFINITION LANGUAGE - MUET-CRP

DATABASE LANGUAGES
A data sub-language (language) consists of two parts
1) DATA DEFINITION LANGUAGE (DDL)
As the name suggests, this language is used to define the various types of data
in the database and their relationship with each other.
FUNCTIONS OF DDL
• Create tables, files, databases and data dictionaries.
• Specify the storage structure of each table on disk.
• Integrity constraints on various tables.
• Security and authorization information of each table.
• Specify the structure of each table.
• Overall design of the Database.
2) DATA MANIPULATION LANGUAGE (DML)
A language that enables users to access or manipulate data (retrieve, insert,
update, delete) as organized by a certain Data Model is called the Data
Manipulation Language (DML). It can be of two types: Data manipulation is applied to external, conceptual and internal levels.
The part of DML that involves data retrieval is called a query language.
Procedural DML - It describes what data is needed and how to get it. For
example: - Relational Algebra.
Non Procedural DML - It describes what data is needed without
specifying how to get it. For example: - Relational calculus.