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_15608800_2 ( number_at_march VARCHAR, class VARCHAR )

### Question ###
Name the number at march when class is j66

### Accurate SQL ###

SELECT number_at_march FROM table_15608800_2 WHERE class = "J66"