Task: Text to Code
Input (English): SQL: SELECT Template_Type_Code FROM Templates EXCEPT SELECT Template_Type_Code FROM Templates
Feedback: steps 1 and 2 change template type code with template id , In step 3 find corresponding template type code of the result .
Output (English): SELECT template_type_code FROM Templates EXCEPT SELECT template_type_code FROM Templates AS T1 JOIN Documents AS T2 ON T1.template_id  =  T2.template_id