Data Definition Language, the SQL tool that Creates, Changes and Drops Database Tables

Part of the You Can Learn SQL series.
By Ken Brown
Editor, YouCanLearnSeries.com
Updated:
September 2, 2004

The Data Definition Language (DDL) is SQL statements that operate on the relational database objects. This is the SQL tool that creates, changes and destroys database tables, views, schemas and catalogs.

There are three commands available in the DDL that allow you to manipulate database objects.

1. CREATE
2. ALTER
3. DROP

The CREATE command allows you to create a new table or view.

Creating a new table with the SQL Create Command

The ALTER command is used to make changes to an existing database object and modifies a table definition by altering, adding, or dropping columns and constraints, or by disabling or enabling constraints and triggers.

Making changes to a database object with the SQL ALTER command.

The DROP command destroys or deletes the database object and removes a table definition and all data, indexes, triggers, constraints, and permission specifications for that table. Any view or stored procedure that references the dropped table must be explicitly dropped by using the DROP VIEW or DROP PROCEDURE statement.

Using the SQL DROP TABLE command.

In review, the Data Definition Language is the SQL tool that creates, changes and destroys database tables, views, schemas and catalogs. The commands are CREATE, ALTER and DROP.

Home| About Us | NewsLetters | Contact Us |

Copyright © 2004-2014 You Can Learn Series

You Can Learn Series Home Page You Can Learn Series
You Can Learn Series Home Page Home            About the creators of YouCanLearnSeriesAbout Us      Contact YouCanLearnSeriesContact Us      Site map of YouCanLearnSeriesSite Map      Privacy Policy of You Can Learn SeriesPrivacy Policy       Terms of Use of You Can Learn Series web siteTerms of Use       YouCanLearnSeries RSS feed for SQL tips and tutorials     
C# and ASP.Net Programming TipsC# and ASP.Net      SQL Tutorial, tips and tricks for DBA'sSQL       Landscaping Tips for Home GardenersLandscaping       WeightLifting Tips for the Young and OldWeightLifting       Good health TipsGoodHealth       Learn about Great Travel DestinationsTravel     Web Business TipsWeb Business     



You Can Learn C# and ASP.Net SeriesC# and ASP.Net

You Can Learn SQL SeriesSQL
  Data Definition LanguageData Definition Language
  Data Manipulation LanguageData Manipulation Language
  What is a DatabaseWhat is a Database
  What is SQLWhat is SQL
  SELECT StatementSELECT Statement
  INSERT StatementINSERT Statement
  DELETE StatementDELETE Statement
  UPDATE StatementUPDATE Statement


You Can Learn Landscaping and Gardening SeriesLandscape Tips
You Can Learn WeightLifting SeriesWeightLift Tips
You Can Learn Good Health SeriesGood Health Tips
You Can Learn Series NewslettersNewsletters
Learn about Great Travel DestinationsTravel
You Can Learn Series Web Business TipsWeb Business Tips

Bill Welter - The Prepared Mind of a Leader




Americas Public Schools