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That was a really badly worded question, but basically when i'm doing:
SELECT SUM(CASE WHEN number = streetNumber AND lname = streetName THEN 1 ELSE 0 END) AS coincidence, COUNT(streetNumber) Amount, Amount-concidence diff FROM records WHERE coincidence < Amount;
But obviously I cant do AMOUNT-COINCIDENCE, so how can I fix this without duplicating the code and having to do this instead:
SELECT SUM(CASE WHEN number = streetNumber AND lname = streetName THEN 1 ELSE 0 END) AS coincidence, COUNT(streetNumber) Amount, COUNT(streetNumber) - SUM(CASE WHEN number = streetNumber AND lname = streetName THEN 1 ELSE 0 END) diff FROM records WHERE SUM(CASE WHEN number = streetNumber AND lname = streetName THEN 1 ELSE 0 END) < COUNT(streetNumber)
This code has been made for the purpose of this question!
I think a subquery is the simplest method:
SELECT r.*, Amount - concidence as diff FROM (SELECT SUM(CASE WHEN number = streetNumber AND lname = streetName THEN 1 ELSE 0 END) AS coincidence, COUNT(streetNumber) as Amount, FROM records r ) r WHERE coincidence < Amount;
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Use a "table expression" to precompute the values, and then you can use a simpler query.
select coincidence, amount, amount - coincidence as diff from ( -- here's the table expression select sum(case when number = streetnumber and lname = streetname then 1 else 0 end) as coincidence, count(streetnumber) as amount, from records ) x where coincidence < amount
Alternatively, some people find CTEs (Common Table Expression) more readable:
with x as ( -- here's the CTE select sum(case when number = streetnumber and lname = streetname then 1 else 0 end) as coincidence, count(streetnumber) as amount, from records ) select coincidence, amount, amount - coincidence as diff from x where coincidence < amount
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if this same value is used in many places, you should create a view with a column or create a computed column in the table (I prefer the view method)
CASE WHEN number = streetNumber AND lname = streetName THEN 1 ELSE 0 END
or if you just use this calculation in that place.. should use a common table expression instead the view
with my_cte as ( SELECT CASE WHEN number = streetNumber AND lname = streetName THEN 1 ELSE 0 END AS coincidence, streetNumber FROM records ) SELECT SUM(coincidence) AS coincidence, COUNT(streetNumber) Amount, COUNT(streetNumber) - SUM(coincidence) diff FROM my_cte having SUM(coincidence) < COUNT(streetNumber)
or if you don't like cte, still can you use an outer apply
SELECT SUM(V.Coincidence) AS coincidence, COUNT(streetNumber) Amount, COUNT(streetNumber) - SUM(V.Coincidence) diff FROM records OUTER APPLY (SELECT CASE WHEN number = streetNumber AND lname = streetName THEN 1 ELSE 0 END AS Coincidence) V HAVING SUM(V.Coincidence) < COUNT(streetNumber)
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- What's wrong with that? Other than your
whereclauses don't match.
- MySQL or SQL Server - tag the one you are using correctly. Highly unlikely you are using both, but if you are that is important information to include explicitly.