Whats the best approach to speed up a slow 'working update statement'. Here is the SQL. PremiseProviderBillings has 1.5 million rows and will grow. The SQL used to be OK now its taking 40 seconds to do the update :-( I would like to do it without the need for select distinct - think thats the slow part
update PremiseProviderBillings set CorrectingCustomerBillId = null where PremiseProviderBillId in (select distinct a.PremiseProviderBillId from PremiseProviderBillings a,PremiseProviderBills b where a.PremiseProviderBillId = b.PremiseProviderBillId and a.CorrectingCustomerBillId = @IN_CustomerBillId);