##Instruction:
Database: cre_Doc_Control_Systems
Total Tables: 11
Total Columns: 35

Table Schemas:

cre_Doc_Control_Systems contains tables such as Ref_Document_Types, Roles, Addresses, Ref_Document_Status, Ref_Shipping_Agents, Documents, Employees, Document_Drafts, Draft_Copies, Circulation_History, Documents_Mailed.
Table Ref_Document_Types has columns such as document_type_code, document_type_description.
document_type_code is the primary key.
Table Roles has columns such as role_code, role_description.
role_code is the primary key.
Table Addresses has columns such as address_id, address_details.
address_id is the primary key.
Table Ref_Document_Status has columns such as document_status_code, document_status_description.
document_status_code is the primary key.
Table Ref_Shipping_Agents has columns such as shipping_agent_code, shipping_agent_name, shipping_agent_description.
shipping_agent_code is the primary key.
Table Documents has columns such as document_id, document_status_code, document_type_code, shipping_agent_code, receipt_date, receipt_number, other_details.
document_id is the primary key.
Table Employees has columns such as employee_id, role_code, employee_name, other_details.
employee_id is the primary key.
Table Document_Drafts has columns such as document_id, draft_number, draft_details.
document_id is the primary key.
Table Draft_Copies has columns such as document_id, draft_number, copy_number.
document_id is the primary key.
Table Circulation_History has columns such as document_id, draft_number, copy_number, employee_id.
document_id is the primary key.
Table Documents_Mailed has columns such as document_id, mailed_to_address_id, mailing_date.
document_id is the primary key.
The shipping_agent_code of Documents is the foreign key of shipping_agent_code of Ref_Shipping_Agents.
The document_status_code of Documents is the foreign key of document_status_code of Ref_Document_Status.
The document_type_code of Documents is the foreign key of document_type_code of Ref_Document_Types.
The role_code of Employees is the foreign key of role_code of Roles.
The document_id of Document_Drafts is the foreign key of document_id of Documents.
The document_id of Draft_Copies is the foreign key of document_id of Document_Drafts.
The draft_number of Draft_Copies is the foreign key of draft_number of Document_Drafts.
The employee_id of Circulation_History is the foreign key of employee_id of Employees.
The document_id of Circulation_History is the foreign key of document_id of Draft_Copies.
The draft_number of Circulation_History is the foreign key of draft_number of Draft_Copies.
The copy_number of Circulation_History is the foreign key of copy_number of Draft_Copies.
The mailed_to_address_id of Documents_Mailed is the foreign key of address_id of Addresses.
The document_id of Documents_Mailed is the foreign key of document_id of Documents.

##Role Access Policy (Column-Level):
Role: DocumentController
Accessible Columns: Ref_Document_Types: ALL COLUMNS; Ref_Document_Status: ALL COLUMNS; Ref_Shipping_Agents: ALL COLUMNS; Documents: ALL COLUMNS; Documents_Mailed: ALL COLUMNS; Addresses: address_id, address_details

Based on the above schema and your role's column-level access policy, generate a SQL query to answer the question. If your role does not have access to the required columns, respond with: "Sorry, I cannot answer."


Question: What document type codes do we have?
Answer: SELECT document_type_code FROM Ref_Document_Types;
Permission: allowed (All required columns are permitted)
Gold SQL: SELECT document_type_code FROM Ref_Document_Types;