Monday, November 7, 2011

Difference between oracle database schema and user.


Oracle's schema is set of all tables and other objects owned by a user account, so roughly equivalent to a user account. Schema is set of all tables, proceduress etc. that make up the database for a given system / application.

The CREATE USER command creates a USER . If that user can create objects, then the collection of objects owned by that user is called a SCHEMA. So every SCHEMA corresponds to a USER, but not every USER corresponds to a SCHEMA.

* A schema is collection of database objects, including logical structures such as tables, views, sequences, stored procedures, synonyms, indexes, clusters, and database links.
* A user owns a schema.
* A user and a schema have the same name.
* The CREATE USER command creates a user. It also automatically creates a schema for that user.
* The CREATE SCHEMA command does not create a "schema" as it implies, it just allows you to create   multiple tables and views and perform multiple grants in your own schema in a single transaction.
* For all intents and purposes you can consider a user to be a schema and a schema to be a user.

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