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_62 (constructor VARCHAR, driver VARCHAR, laps VARCHAR, grid VARCHAR)

### Question ###
who is the constructor when the laps is less than 68, the grid is more than 20 and the driver is thierry boutsen?

### Accurate SQL ###

SELECT constructor FROM table_name_62 WHERE laps < 68 AND grid > 20 AND driver = "thierry boutsen"