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_46 (length__m_ VARCHAR, name VARCHAR)

### Question ###
What is the Length (m) of the Koppenberg course?

### Accurate SQL ###

SELECT length__m_ FROM table_name_46 WHERE name = "koppenberg"