你是什么数据库。就用什么函数去截取拼就行了呀
比如mysql
select
a.tt,
concat(substr(a.tt,1,4),'-',substr(a.tt,5,2),'-',substr(a.tt,7,2)) as 转换后
from (select '20220705' as tt) a

oracel中
select
a.tt,
substr(a.tt,1,4)||'-'||substr(a.tt,5,2)||'-'||substr(a.tt,7,2) as 转换后
from (select '20220705' as tt from dual) a

sql serve中
select
a.tt,
SUBSTRING(a.tt,1,4)+'-'+SUBSTRING(a.tt,5,2)+'-'+SUBSTRING(a.tt,7,2) as 转换后
from (select '20220705' as tt) a
