On how many different dates was the episode written by Charlie Day aired for the first time?
CREATE TABLE table_29273115_1 (original_air_date VARCHAR, written_by VARCHAR)
SELECT COUNT(original_air_date) FROM table_29273115_1 WHERE written_by = "Charlie Day"
<s>[INST] Write mssql query to answer the following question given the database schema. Schema: CREATE TABLE table_29273115_1 (original_air_date VARCHAR, written_by VARCHAR) Question: On how many different dates was the episode written by Charlie Day aired for the first time? [/INST] SELECT COUNT(original_air_date) FROM table_29273115_1 WHERE written_by = "Charlie Day" </s>