Task: Text to Code
Input (English): SQL: SELECT DISTINCT Template_Type_Description FROM Ref_Template_Types
Feedback: Ensure that template is used in a Document .
Output (English): SELECT DISTINCT T1.template_type_description FROM Ref_template_types AS T1 JOIN Templates AS T2 ON T1.template_type_code  = T2.template_type_code JOIN Documents AS T3 ON T2.Template_ID  =  T3.template_ID