I have a query below that I would like to change into a NOT EXITS to see if it would be more efficient. How would
I convert the below query into a COUNT with NOT EXITS?
select count(distinct(serv_item.serv_item_id)) from serv_item where serv_item.status = '6' and serv_item.serv_item_id not in (select pbi_bill_activation.tbs_id from pbi_bill_activation where pbi_bill_activation.tbs_id_type in ('EUL','OFFER','S800I','SCRDI','SDIDI'));
Here is a sample NOT IN query:
select * from MyTable where MyCol not in ( select MyCol from MyOtherTable )The following query has the same results, though it uses a NOT EXISTS. Not the sub-query is correlated.
select * from MyTable where not exists ( select * from MyOtherTable where MyCol = MyTable.MyCol )Although you could easily rewrite your query using my example, I'll do it here to further illustrate the concept.
select count(distinct(serv_item.serv_item_id)) from serv_item where serv_item.status = '6' and not exists ( select pbi_bill_activation.tbs_id from pbi_bill_activation where pbi_bill_activation.tbs_id_type in ('EUL','OFFER','S800I','SCRDI','SDIDI') and pbi_bill_activation = serv_item.serv_item_id )
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