How many students for both genders graduated from a 2-year institute in Alabama in 2011?
2-year institute refers to cohort = '2y all'; Alabama refers to state = 'Alabama'; in 2011 refers to year = 2011; T2.gender = 'B' means both genders;
SELECT SUM(T2.grad_cohort) FROM institution_details AS T1 INNER JOIN institution_grads AS T2 ON T2.unitid = T1.unitid WHERE  T2.cohort = '2y all' AND T2.year = 2011 AND T1.state = 'Alabama'