Question: How many more students in total graduated from Central Alabama Community College in 2012 than in 2011?
SQL: SELECT SUM(CASE WHEN T2.year = 2012 THEN T2.grad_cohort ELSE 0 END) - SUM(CASE WHEN T2.year = 2011 THEN T2.grad_cohort ELSE 0 END) FROM institution_details AS T1 INNER JOIN institution_grads AS T2 ON T2.unitid = T1.unitid WHERE T1.chronname = 'Central Alabama Community College'