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_21781578_2 ( season_no VARCHAR, production_code VARCHAR )

### Question ###
What was the season number for production code E2110?

### Accurate SQL ###

SELECT season_no FROM table_21781578_2 WHERE production_code = "E2110"