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

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.