题解 | 统计所有课程参加培训人次
统计所有课程参加培训人次
https://www.nowcoder.com/practice/98aad5807cf34a3b960cc8a70ce03f53
SELECT SUM(num) AS staff_nums
FROM (
SELECT CASE WHEN course IS NULL THEN 0
ELSE length(course) - length(replace(course,',',''))+1 END AS num
FROM cultivate_tb
) sub

