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_2970978_1 (ave_attendance INTEGER, ___ave_on_prev_season VARCHAR)

### Question ###
What is the least value for average attendance when average on previous season is +644?

### Accurate SQL ###

SELECT MIN(ave_attendance) FROM table_2970978_1 WHERE ___ave_on_prev_season = "+644"