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_55 (chng VARCHAR, rank VARCHAR, prev VARCHAR)

### Question ###
What chng has a rank greater than 6, with 12 as a prev?

### Accurate SQL ###

SELECT chng FROM table_name_55 WHERE rank > 6 AND prev = 12