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:
“Computers are good at swift, accurate computation and at storing great masses of information. The brain, on the other hand, is not as efficient a number cruncher and its memory is often highly fallible; a basic inexactness is built into its design. The brain’s strong point is its flexibility. It is unsurpassed at making shrewd guesses and at grasping the total meaning of information presented to it.”
—Jeremy Campbell (b. 1931)