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_28652521_1 ( singer_part_number VARCHAR, storage_case VARCHAR )

### Question ###
What's the singer part number of the buttonholer whose storage case is a green plastic box?

### Accurate SQL ###

SELECT singer_part_number FROM table_28652521_1 WHERE storage_case = "green plastic box"