1.SUBSTRING

2.SUBSTRING_INDEX

3. right/left

4.POSITION

sql实例

select left(right(SUBSTRING_INDEX(data_out,":",7),10),3) from check_post01 where day_online='2017-06-08 00:00:00';

select SUBSTRING(data_out,18,20) from check_post01 where day_online='2017-06-08 00:00:00';