题解 | 统计所有课程参加培训人次

select sum(course1)+sum(course2)+sum(course3) staff_nums
from(
SELECT 
 CASE WHEN course LIKE'%1%' THEN 1 else 0 end course1,
 CASE WHEN course LIKE'%2%' THEN 1 else 0 end course2,
 CASE WHEN course LIKE'%3%' THEN 1 else 0 end course3
FROM cultivate_tb
)a