What is the average year that the club located in enfield was founded with an unknown coach?
CREATE TABLE table_name_87 (founded INTEGER, coach VARCHAR, location VARCHAR)
SELECT AVG(founded) FROM table_name_87 WHERE coach = "unknown" AND location = "enfield"
<s>[INST] Write mssql query to answer the following question given the database schema. Schema: CREATE TABLE table_name_87 (founded INTEGER, coach VARCHAR, location VARCHAR) Question: What is the average year that the club located in enfield was founded with an unknown coach? [/INST] SELECT AVG(founded) FROM table_name_87 WHERE coach = "unknown" AND location = "enfield" </s>