Why using cross apply return extra row. Isn't it should work similar to INNER JOIN? The result I'd expect is
QuoteID controlNo etc MaxQuoteID COntrolNo
10101 1111 something15 10101 1111
Sample Data:
-- create first example table
drop table if exists #test1
create table #test1 (QuoteID int, controlNo int, etc varchar(100))
insert into #test1 values
(1111, 1111,'something1'),
(10101, 1111,'something15'),
(2222, 2222,'something2'),
(3333, 3333,'something3'),
(3333, 30303,'something35'),
(4444, 4444,'something4')
select * from #test1
--create second example table
drop table if exists #test2
create table #test2 (QuoteID int, ControlNo int)
insert into #test2 values
(1111,1111),
(10101,1111)
select * from #test2
-- resutl query 1. This one works as expected
select *
from #test1 t
inner join (select max(QuoteID) as MaxQuoteID, COntrolNo from #test2 group by ControlNo) tt ON t.QuoteID = tt.MaxQuoteID
-- But why this one doesnt work?
select *
from #test1 t
cross apply
(
-- subquery returns a single quoteid 10101, which is what I need
select max(QuoteID) as QuoteID
from #test2 tt
where tt.QuoteID = t.QuoteID
group by ControlNo
) a
Both of the query are not the same.
In Query 1, you wanted the max(QuoteID)
group by controlNo
In Query 2, you are getting the max(QuoteID)
for each controlNo
If you wanted equivalent using CROSS APPLY
, should be
select *
from #test1 t
cross apply
(
select max(tt.QuoteID) as QuoteID, tt.controlNo
from #test2 tt
group by tt.controlNo
having max(QuoteID) = t.QuoteID
) a