In relational databases, the 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 the SHOW command of MySQL, the DESCRIBE command of Oracle, and the \d command of PostgreSQL.
=> select count(table_name) from information_schema.tables; count ------- 99 (1 row) => select column_name, data_type, column_default, is_nullable from information_schema.columns where table_name='alpha'; column_name | data_type | column_default | is_nullable -------------+-----------+----------------+------------- foo | integer | | YES bar | character | | YES (2 rows) => select * from information_schema.information_schema_catalog_name; catalog_name -------------- johnd (1 row)
Famous quotes containing the word information:
“Phenomenal nature shadows him wherever he goes. Clouds in the staring sky transmit to one another, by means of slow signs, incredibly detailed information regarding him. His inmost thoughts are discussed at nightfall, in manual alphabet, by darkly gesticulating trees. Pebbles or stains or sunflecks form patterns representing in some awful way messages which he must intercept. Everything is a cipher and of everything he is the theme.”
—Vladimir Nabokov (1899–1977)