ClickHouse/docs/en/system_tables/system.columns.rst

system.columns
--------------

Contains information about the columns in all tables.
You can use this table to get information similar to ``DESCRIBE TABLE``, but for multiple tables at once.
::
  database String           - Name of the database the table is located in.
  table String              - Table name.
  name String               - Column name.
  type String               - Column type.
  default_type String       - Expression type (DEFAULT, MATERIALIZED, ALIAS) for the default value, or an empty string if it is not defined.
  default_expression String - Expression for the default value, or an empty string if it is not defined.