CREATE TABLE Ref_document_types (document_type_code VARCHAR2, document_type_name VARCHAR2, document_type_description VARCHAR2)

Show all document type codes, document type names, document type descriptions.
SELECT document_type_code, document_type_name, document_type_description FROM Ref_document_types
SELECT "document_type_code", "document_type_name", "document_type_description" FROM "Ref_document_types"