Improve the performance of a SQL Query via SQL Server - sql

Question

I'm looking for improve the performance of the Last Year Attended query. Right now, its taking 20+ minutes to run this block.
The LYA take the most recent year attended for a particular event and finds the year they attended prior to the max. For example if they attended in 2018 for an event, the query will look for the last year attended prior to 2018.
LYA for 2018 should return a Null
The data should return the following:
CompanyID MarketID Industry LAST YEAR ATTENDED
-------------------------------------------------------
123456 1234 GIFT 2018
123457 1234 HOME 2017
123458 1234 GIFT 2018
123459 1234 HOME 2018
123460 1234 APPAREL 2018
123461 1234 HOME 2018
123462 1234 HOME 2017
123463 1234 APPAREL 2018
Can anyone assist?
SELECT DISTINCT
COMPANYID, MARKETID, INDUSTRY,
[LAST YEAR ATTENDED] = (SELECT MAX(YEAR(attdate))
FROM v_marketatt va
WHERE va.companyid = vm.companyid
AND YEAR(attdate) <> (SELECT MAX(YEAR(attdate))
FROM v_marketatt vb
WHERE vb.companyid = vm.companyid)
AND MARKETCODE LIKE 'SM1%')
FROM
v_marketatt vm
WHERE
MARKETID IN (835, 1032, 1101)
UPDATE:
Found that is version is more efficient than the rest. Run time down to 7 minutes on a clone. Instead of allowing the subquery to dip into my view twice, had it dip once.
select
DISTINCT COMPANYID,
MARKETID,
INDUSTRY,
CSTATUS,
[LAST YEAR ATTENDED] = (select max(year(attdate)) from v_marketatt va where year(attdate) <> (select max(year(attdate)) from v_marketatt) AND MARKETCODE LIKE 'SM1%' AND va.COMPANYID = vm.COMPANYID)
from v_marketatt vm
WHERE MARKETID IN (835,1032,1101)
;
Thanks to all who responded.

Answer 1

The field [LAST YEAR ATTENDED] has a subquery that computes the max year on each iteration.You can try moving this piece of query to a join something like
select DISTINCT COMPANYID, MARKETID, INDUSTRY,
[LAST YEAR ATTENDED]
from v_marketatt vm
inner join
( select max(year(attdate)) as [LAST YEAR ATTENDED]
from v_marketatt ivm
where year(ivm.attdate) <> (select max(year(attdate))
from v_marketatt vb
where vb.companyid =
ivm.companyid)
AND MARKETCODE LIKE 'SM1%')va on va.companyid = vm.companyid
--where companyid not in (select distinct companyid from
v_marketatt where marketid in (602))
WHERE MARKETID IN (835,1032,1101)
I have not run this query , there could be some minor corrections on syntax , but if you get the concept it should be easy to pick and fix.

Answer 2

apologies for syntax, I'm throwing this together quickly. But I suspect making use a CTE should improve performance dramatically. I'm also not quite sure what you're doing here:
WHERE va.companyid = vm.companyid
AND YEAR(attdate) <> (SELECT MAX(YEAR(attdate))
FROM v_marketatt vb)
AND MARKETCODE LIKE 'SM1%'
So I've left that piece alone. Try something like this, which should help, and possible clarification on the part I've noted above might unlock other things to tweak.
;with Year_CTE (year)
as
(SELECT MAX(YEAR(attdate), va.companyid)
FROM v_marketatt va
WHERE va.companyid = vm.companyid
AND YEAR(attdate) <> (SELECT MAX(YEAR(attdate))
FROM v_marketatt vb)
AND MARKETCODE LIKE 'SM1%')
SELECT DISTINCT
COMPANYID, MARKETID, INDUSTRY,
vb.[YEAR]
FROM
v_marketatt vm
join Year_CTE vb on vb.companyid = vm.companyid
WHERE
MARKETID IN (835, 1032, 1101)

Answer 3

IF you need 'the one before this one' I'd suggest to use LEAD() or LAG() functions.
Although I'm not quite sure I fully understand your example (see Thorsten Kettners comments), going by the explanation I think what you want is something along the lines of:
;WITH years
AS (
SELECT COMPANYID, MARKETID, INDUSTRY, YEAR_ATTENDED = Year(attdate)
FROM v_marketatt
WHERE MARKETID IN (835, 1032, 1101)
AND MARKETCODE LIKE 'SM1%' -- not sure about this one, the example isn't very clear
GROUP BY COMPANYID, MARKETID, INDUSTRY, Year(attdate)
),
last_ones
AS (
SELECT row_nbr = ROW_NUMBER() OVER ( PARTITION BY COMPANYID, MARKETID, INDUSTRY ORDER BY YEAR_ATTENDED DESC),
COMPANYID, MARKETID, INDUSTRY,
LAST_YEAR_ATTENDED = YEAR_ATTENDED,
PREV_YEAR_ATTENDED = LEAD(YEAR_ATTENDED, 1, NULL) OVER (PARTITION BY COMPANYID, MARKETID, INDUSTRY ORDER BY YEAR_ATTENDED DESC)
FROM years
)
SELECT COMPANYID, MARKETID, INDUSTRY,
LAST_YEAR_ATTENDED,
PREV_YEAR_ATTENDED
FROM last_ones
WHERE row_nbr = 1
Since I don't have the tables nor the data here, I haven't tested the query, but I hope it will get you going...