CREATE TABLE accounts (account_id DECIMAL, statement_id DECIMAL, account_details TEXT)
CREATE TABLE statements (statement_id DECIMAL, statement_details TEXT)
CREATE TABLE ref_budget_codes (budget_type_code TEXT, budget_type_description TEXT)
CREATE TABLE projects (project_id DECIMAL, project_details TEXT)
CREATE TABLE documents (document_id DECIMAL, document_type_code TEXT, project_id DECIMAL, document_date TIME, document_name TEXT, document_description TEXT, other_details TEXT)
CREATE TABLE documents_with_expenses (document_id DECIMAL, budget_type_code TEXT, document_details TEXT)
CREATE TABLE ref_document_types (document_type_code TEXT, document_type_name TEXT, document_type_description TEXT)

What are the document ids for the budget type code 'SF'?
SELECT document_id FROM documents_with_expenses WHERE budget_type_code = 'SF'
SELECT "document_id" FROM "documents_with_expenses" WHERE "budget_type_code" = 'SF'