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_1 (class VARCHAR, no_built VARCHAR, operator VARCHAR)

### Question ###
What class has less than 12 numbers built operated by southern?

### Accurate SQL ###

SELECT class FROM table_name_1 WHERE no_built < 12 AND operator = "southern"