select t.id
,sum(if(t.sms_days<7,(REPLACE((case when int(t.content rlike 'préstamo')>0 then if(length(regexp_extract(t.content,'[^\x00-\xff]([0-9]+[.|,]+[0-9]+)peso',1))>0,regexp_extract(t.content,'[^\x00-\xff]([0-9]+[.|,]+[0-9]+)peso',1),null) else 0 end),',','')),Null)) as sum_amount_7d
from dm_tmp.biz_base t group by t.id;
这段代码怎么解释,regexp_extract函数的参数是什么意思?