mysql - 将mysql结果求和到指定组中

Question

    SELECT 
    f.hmis, sa.number_of_computers, sa.service_area
FROM
    facility_service_area sa,
    facility f
WHERE
    f.hmis = sa.facility_hmis


hmis   comp serv_area
80703   3   MCH
80706   1   LD
80701   2   ART
80701   3   ART
80701   2   LD
80701   3   LD
80701   2   MCH
80701   1   MCH
80702   4   MCH
80707   1   MCH
80707   4   MCH

我想对每个 hmi 下每个指定服务区域中的所有计算机进行求和，结果如下所示。

hmis   comp. Service_area
80703   3   MCH
80706   1   LD
80701   5   ART
80701   5   LD
80701   3   MCH
80702   4   MCH
80707   4   MCH

Answer 1

Use GROUP BY with SUM() aggregate function. 
SELECT f.hmis,
       SUM(sa.number_of_computers),
       sa.service_area
FROM facility_service_area sa,
     facility f
WHERE f.hmis = sa.facility_hmis
GROUP BY sa.service_area


Also you can use INNER JOIN for this.

SELECT f.hmis, SUM(sa.number_of_computers), sa.service_area
FROM facility_service_area sa INNER JOIN
facility f
ON f.hmis = sa.facility_hmis
GROUP BY sa.service_area