-- Database schema
| incidents : case_number [ TEXT ] primary_key , date [ DATE ] , location [ TEXT ] , subject_statuses [ TEXT ] , subject_weapon [ TEXT ] , subjects [ TEXT ] , subject_count [ INTEGER ] , officers [ TEXT ] | officers : case_number [ TEXT ] officers.case_number = incidents.case_number , race [ TEXT ] , gender [ TEXT ] , last_name [ TEXT ] , first_name [ TEXT ] , full_name [ TEXT ] | subjects : case_number [ TEXT ] subjects.case_number = incidents.case_number , race [ TEXT ] , gender [ TEXT ] , last_name [ TEXT ] , first_name [ TEXT ] , full_name [ TEXT ] |
-- -- Of the black officers, how many of them investigated cases between the years 2010 and 2015?

SELECT COUNT(T1.case_number) FROM officers AS T1 INNER JOIN incidents AS T2 ON T2.case_number = T1.case_number WHERE T1.race = 'B' AND T2.date BETWEEN '2010-01-01' AND '2015-12-31';