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Oracle Database provides information about all of the tables, views, columns, and procedures in a database. This information about information is known as metadata. [1] It is stored in two locations: data dictionary tables (accessed via built-in views) and a metadata registry.
The DUAL table is a special one-row, one-column table present by default in Oracle and other database installations. In Oracle, the table has a single VARCHAR2(1) column called DUMMY that has a value of 'X'. It is suitable for use in selecting a pseudo column such as SYSDATE or USER.
Oracle Database is available by several service providers on-premises, on-cloud, or as a hybrid cloud installation. It may be run on third party servers as well as on Oracle hardware (Exadata on-premises, on Oracle Cloud or at Cloud at Customer). [5] Oracle Database uses SQL for database updating and retrieval. [6]
In relational databases, the information schema (information_schema) is an ANSI-standard set of read-only views that provide information about all of the tables, views, columns, and procedures in a database. [1] It can be used as a source of the information that some databases make available through non-standard commands, such as:
The database schema is the structure of a database described in a formal language supported typically by a relational database management system (RDBMS). The term "schema" refers to the organization of data as a blueprint of how the database is constructed (divided into database tables in the case of relational databases).
The DROP statement destroys an existing database, table, index, or view. A DROP statement in SQL removes a component from a relational database management system (RDBMS). The types of objects that can be dropped depends on which RDBMS is being used, but most support the dropping of tables , users , and databases .
Analyze information on a table, index, or cluster; Establish auditing options; Add comments to the data dictionary; So Oracle Database DDL commands include the Grant and revoke privileges which is actually part of Data control Language in Microsoft SQL server. Syntax for grant and revoke in Oracle Database:
Oracle Corporation calls these variables "substitution variables". Programmers can use them anywhere in a SQL or PL/SQL statement or in SQL Plus commands. They can be populated by a literal using DEFINE or from the database using the column command.