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_50 ( diameter__km_ INTEGER, latitude VARCHAR, year_named VARCHAR, longitude VARCHAR )

### Question ###
What is the diameter for 1997 when longitude is 212.0e and latitude is 47.0n?

### Accurate SQL ###

SELECT MIN(diameter__km_) FROM table_name_50 WHERE year_named = 1997 AND longitude = "212.0e" AND latitude = "47.0n"