Table schema:
CREATE TABLE Templates (template_type_code VARCHAR, template_id VARCHAR); 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"?
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"