How many episodes were written only by William N. Fordes?
CREATE TABLE table_12159115_3 (series__number VARCHAR, written_by VARCHAR)
SELECT COUNT(series__number) FROM table_12159115_3 WHERE written_by = "William N. Fordes"
<s>[INST] Write mssql query to answer the following question given the database schema. Schema: CREATE TABLE table_12159115_3 (series__number VARCHAR, written_by VARCHAR) Question: How many episodes were written only by William N. Fordes? [/INST] SELECT COUNT(series__number) FROM table_12159115_3 WHERE written_by = "William N. Fordes" </s>