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_68 (marriage VARCHAR, became_duchess VARCHAR)

### Question ###
Which Marriage has a Became Duchess of 12 december 1666?

### Accurate SQL ###

SELECT marriage FROM table_name_68 WHERE became_duchess = "12 december 1666"