In relational databases, the information schema (information_schema) is an ANSI-standard set of read-only views which provide information about all of the tables, views, columns, and procedures in a database. It can be used as a source of the information which some databases make available through non-standard commands, such as:
SHOW
command of MySQLDESCRIBE
command of Oracle's SQL*Plusd
command in psql (PostgreSQL's default command-line program).Implementation
As a notable exception among major database systems, Oracle does not as of 2015 implement the information schema. An open-source project exists to address this.
RDBMSs which support information_schema include:
RDBMSs which do not support information_schema include:
References
Information schema Wikipedia(Text) CC BY-SA