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_name_49 (laps INTEGER, driver VARCHAR, grid VARCHAR, constructor VARCHAR)

### Question ###
What is the average Laps for a grid smaller than 17, and a Constructor of williams - bmw, driven by jenson button?

### Accurate SQL ###

SELECT AVG(laps) FROM table_name_49 WHERE grid < 17 AND constructor = "williams - bmw" AND driver = "jenson button"