SELECT document_type_code FROM Ref_document_types WHERE document_type_name  =  "Paper"
What is the document type code for document type "Paper"?
SELECT document_type_code FROM Ref_document_types WHERE document_type_name = `` Paper ''
select document_type_code from ref_document_types where document_type_name = value
What is the document type code for document type `` Paper '' ?