我想念什么？
select datediff(month,d.birthdate,d.min_claimdate) as age_months, count(datediff(month,d.birthdate,d.min_claimdate)) as cnt
from (
select a.member_id, c.birthdate, b.diagnosis_code, min(b.claimdate) as min_claimdate
from
table_A a
join
table_B b
on a.claim_id=b.claim_id
left join
table_C c
on a.member_id=c.member_id
group by 1,2,3
) as d
group by datediff(month,d.birthdate,d.min_claimdate)
order by datediff(month,d.birthdate,d.min_claimdate)
我不认为Teradata具有日期函数。 try，例如：：
MONTHS_BETWEEN(d.birthdate,d.min_claimdate)
link for fn：
https：//docs.teradata.com/r/enterprise_intelliflex_vmware/sql-date--date-mand-time-fime-functions-and-time-functions-and-datempetime-and--interval--interval-functions-and-functions-and-functions-and-ymonths/months_bets_bets_betnes/months_betney/sonthss_bets_bets_bets_bettions_bettions_bettim timpe