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_16028459_2 (bills_first_downs INTEGER, opponents VARCHAR)

### Question ###
How many first downs did the bills have when their opponent had 6

### Accurate SQL ###

SELECT MIN(bills_first_downs) FROM table_16028459_2 WHERE opponents = 6