你要用mysql数据库处理?
select
substring_index(
substring_index(
t.com,
',',
b.help_topic_id + 1
),
',' ,- 1
) AS 处理后
from (
select 'f005,13466664685,f0006,3667477,f0008,3555' as com
) t
JOIN mysql.help_topic b ON b.help_topic_id < (
length(t.com) - length(
REPLACE (t.com, ',', '')) + 1)