Set flag based on mapping table with no primary key?

Question

I have a mapping table that contains: Start_Dt and End_Dt.

I have a table that has Member_ID and Received_Dt.

What I want to do is set a flag based on whether or not the Received Dt is between the Start_Dt and END Dt.

I don't have a primary key so I'm not sure the most effective place to start.

  select 
Z.Member_ID, 
Z.Received_Dt, 
  FLAG=CASE WHEN A.Received_Date between W.ST_DT AND W.END_DT THEN 'Yes' ELSE NULL END
from #Member Z 
left join dbo.Weeks W

Answer 1

Very ill-defined question but I guess you need something like:

update member b set flag = (
  select case when count(*) > 0 then 'y' else 'n' end 
  from mapping m 
  where b.received_dt >= m.start_dt 
    and b.received_dt <= m.end_dt
)