Structured query language features of biography

Its original inception was based on a paper by Edgar F. Chamberlin and Raymond F. The following table shows the release dates of major SQL standards along with a brief description of the changes made in each version. In our Introduction to Databases we discussed the concept of a schema as a definition of the structure of a database.

In SQL, a schema is a collection of database objects, such as tables, views, and indexes. A schema is owned by a database user and has the same name as the user. A database user can own multiple schemas, and a schema can be owned by multiple users.

Sql language

A schema can also be owned by a role, which is a collection of users. A role can own multiple schemas, and a schema can be owned by multiple roles. There are several practical reasons for which we would want to create multiple schemas. For example, a database might be used by both a Human Resources and Healthcare Management application. Creating two separate schemas would ensure that data for each application is kept secure from unauthorized users.

Multiple schemas are also used for testing and development processes.

Sql definition

Large structural changes to an application may require a new scheme to be created. New features can be developed in the new schema while the old schema is still being used by the application. The following command creates a new schema named MedApp and assigns it to the user MedAdmin.