Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_20174050_1 (release_date VARCHAR, story__number VARCHAR)

### Question ###
How many different release dates are there for the audio book with a story number 7?

### Accurate SQL ###

SELECT COUNT(release_date) FROM table_20174050_1 WHERE story__number = 7