Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE Templates (template_type_code VARCHAR, template_id VARCHAR)
TABLE: CREATE TABLE Documents (template_id VARCHAR, document_name VARCHAR)

### Question ###
What is the template type code of the template used by document with the name "Data base"?

### Accurate SQL ###

SELECT T1.template_type_code FROM Templates AS T1 JOIN Documents AS T2 ON T1.template_id = T2.template_id WHERE T2.document_name = "Data base"