What is the production code for the episode with 8.56 million U.S. viewers?
CREATE TABLE table_22181917_2 (production_code VARCHAR, us_viewers__millions_ VARCHAR)
SELECT production_code FROM table_22181917_2 WHERE us_viewers__millions_ = "8.56"
<s>[INST] Write mssql query to answer the following question given the database schema. Schema: CREATE TABLE table_22181917_2 (production_code VARCHAR, us_viewers__millions_ VARCHAR) Question: What is the production code for the episode with 8.56 million U.S. viewers? [/INST] SELECT production_code FROM table_22181917_2 WHERE us_viewers__millions_ = "8.56" </s>