29 Nov 2007
A bit late but maybe you can try to look in the following direction:
select distinct customers from month_12_table
union
select distinct customers from month_11_table
union
.....
.....
union
select distinct customers from month_3_table
minus
select distinct customers from month_2_table
minus
select distinct customers from month_1_table
minus
select distinct customers from month_0_table
30 Nov 2007
thanks,ohuibers,
i haved solved the problem the same way as your advice
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Hi,I need to compute a kpi named "Low-grade Silent Customers"
which means customers that haven't use our specific service for
3 months to 1 year.In our data warehouse,we store specific service
usage records in separate tables by month,and each table has more
than one hundred million recodes,who can give me a smart sql?