Which Marriage has a Became Duchess of 12 december 1666?
CREATE TABLE table_name_68 (
    marriage VARCHAR,
    became_duchess VARCHAR
)
SELECT marriage FROM table_name_68 WHERE became_duchess = "12 december 1666"
Below are sql tables schemas paired with instruction that describes a task. Using valid SQLite, write a response that appropriately completes the request for the provided tables. ### Instruction: Which Marriage has a Became Duchess of 12 december 1666? ### Input: CREATE TABLE table_name_68 (
    marriage VARCHAR,
    became_duchess VARCHAR
) ### Response: SELECT marriage FROM table_name_68 WHERE became_duchess = "12 december 1666"