Table1:
Shop
Manager
Date
Table2:
Shop
Date
Sales
I need to get Table2 with Manager field from Table1. I did the following trick:
select
t1.[Shop]
,t1.[Date]
,t1.[Sum]
,t2.[Manager]
from t1
left join t2
on t1.[Shop] = t2.[Shop]
and t2.[Date] = (select max(t2.[Date]) from t2
where t2.[Shop] = t1.[Shop]
and t2.[Date] < t1.[Date])
It works, but subquerying is very slow, so I wonder if there is more elegant and fast way to do so?
Some sample data to play around: http://pastebin.com/uLN6x5JE
may seem like a round about way but join on a single condition is typically faster
select t12.[Shop], t12.[Date], t12.[Sum]
, t12.[Manager]
from
( select t1.[Shop], t1.[Date], t1.[Sum]
, t2.[Manager]
, row_number() over (partition by t2.[Shop] order by t2.[Date] desc) as rn
from t1
join t2
on t2.[Shop] = t1.[Shop]
and t1.[Date] < t1.[Date]
) as t12
where t12.rn = 1
union
select t1.[Shop], t1.[Date], t1.[Sum]
, null as [Manager]
from t1
left join t2
on t2.[Shop] = t1.[Shop]
and t1.[Date] < t1.[Date]
group by t1.[Shop], t1.[Date], t1.[Sum]
having count(*) = 1
You may get much better performance by adding a covering index on t2 if you don't already have one:
create index T2ShopDate on t2 ([Shop], [Date]) include ([Manager])
Here is a version that uses a CTE to find all maximum manager dates first and then join back to t2 to get the manager:
;with MaxDates ([Shop], [Date], [Sum], [MaxMgrDate]) as
(
select
t1.[Shop]
,t1.[Date]
,t1.[Sum]
,max(t2.[Date])
from t1
left join t2
on t2.[Shop] = t1.[Shop]
and t2.[Date] < t1.[Date]
group by
t1.[Shop]
,t1.[Date]
,t1.[Sum]
)
select
MaxDates.[Shop]
,MaxDates.[Date]
,MaxDates.[Sum]
,t2.[Manager]
from MaxDates
inner join t2
on t2.[Date] = MaxDates.[MaxMgrDate]
You might be able to remove the second join back to t2 by using row_number():
;with MaxDates ([Shop], [Date], [Sum], [Manager], [RowNum]) as
(
select
t1.[Shop]
,t1.[Date]
,t1.[Sum]
,t2.[Manager]
,row_number() over (partition by (t1.[Shop]) order by t2.[Date] desc)
from t1
left join t2
on t2.[Shop] = t1.[Shop]
and t2.[Date] < t1.[Date]
)
select *
from MaxDates
where RowNum = 1
Related
I know that LEAD & LAG functions are there to achieve the task to get previous & next data row. my question is how to achieve the same goal in old sql server where LEAD & LAG not present. please suggest some good approach to retrieve Previous & Next data row with LEAD & LAG function. Thanks
Here i am sharing one example which is working fine.
Create table #test
(
ID int identity(1,1),
Quarter nvarchar(20)
)
insert into #test values
('1Q 2010'),
('2Q 2010'),
('3Q 2010'),
('4Q 2010'),
('FY 2010')
select * from #test
select PrevID,PrevQuarter,CurrID,CurrQuarter
from
(
select Lag(ID,1) over(order by ID)PrevID ,LAG(Quarter,1)over(order by ID)PrevQuarter,
ID as CurrID,Quarter as CurrQuarter
from #test
)t
where CurrID=4
You could use correlated TOP subqueries in lieu of LEAD and LAG:
SELECT PrevID, PrevQuarter, CurrID, CurrQuarter
FROM
(
SELECT
(SELECT TOP 1 ID FROM #test t2
WHERE t2.ID < t1.ID ORDER BY t2.ID DESC) PrevID,
(SELECT TOP 1 Quarter FROM #test t2
WHERE t2.ID < t1.ID ORDER BY t2.ID DESC) PrevQuarter,
ID AS CurrID, Quarter AS CurrQuarter
FROM #test t1
) t
WHERE CurrID = 4;
Here is a working demo.
there are many ways to do it. Here are 2
Self Join:
If ID is not continuous, use row_number() to generate one
select p.ID as PrevID, p.Quarter as PrevQuarter,
c.ID as CurrID, c.Quarter as CurrQuarter
from #test c
left join #test p on c.ID = p.ID + 1
where c.ID = 4
using APPLY():
select p.ID as PrevID, p.Quarter as PrevQuarter,
c.ID as CurrID, c.Quarter as CurrQuarter
from #test c
outer apply
(
select top 1 ID, Quarter
from #test x
where x.ID < c.ID
order by x.ID desc
) p
where c.ID = 4
Say I want to select the posts that has certain tags or matches the keyword.
select t1.*
from (
select p.*, count(p.id) from plainto_tsquery('hElLo') AS q , post p
left join post_tag pt on pt.post_id = p.id
left join tag t on t.id = pt.tag_id
WHERE (tsv ## q) or t.id in (2,3)
group by p.id
) as t1
order by count desc, ts_rank_cd(t1.tsv, plainto_tsquery('hElLo')) desc
limit 5;
the above does select what I want. In tsv, I gave title A weight and description D weight. it now becomes pretty pointless when sorting by count because each entry has the same weight. Is it possible to do things like if this row is picked from t.id in (2,3), they get to sorted to the first, then sort by ts_rank_cd, or give each match tag 'A' weight, title become B weight and description is D?
Try CASE WHEN
select t1.*
from (
select p.*, count(p.id),
(CASE WHEN t.id in (2,3) THEN 1 ELSE 2 END) as ranking
from plainto_tsquery('hElLo') AS q , post p
left join post_tag pt on pt.post_id = p.id
left join tag t on t.id = pt.tag_id
WHERE (tsv ## q) or t.id in (2,3)
group by p.id
) as t1
order by count desc, ranking asc, ts_rank_cd(t1.tsv, plainto_tsquery('hElLo')) desc
limit 5;
Edited(Correct Answer):
select t1.*
from (
select p.*, count(p.id),
COUNT(1) filter(where t.id in (2,3)) ranking
from plainto_tsquery('hElLo') AS q , post p
left join post_tag pt on pt.post_id = p.id
left join tag t on t.id = pt.tag_id
WHERE (tsv ## q) or t.id in (2,3)
group by p.id
) as t1
order by count desc, ranking asc, ts_rank_cd(t1.tsv, plainto_tsquery('hElLo')) desc
limit 5;
I'm not sure why the count would be the same, but you can add more keys to the order by:
order by count desc,
(t.id in (2, 3)) desc,
ts_rank_cd(t1.tsv, plainto_tsquery('hElLo')) desc ;
The desc is because true > false, and you want the true values to be first.
Below sample query is a part of my main query. I found SORT operator in below query is consuming 30% of the cost.
To avoid SORT, there is need of creation of Indexes. Is there any other way to optimize this code.
SELECT TOP 1 CONVERT( DATE, T_Date) AS T_Date
FROM TableA
WHERE ID = r.ID
AND Status = 3
AND TableA_ID >ISNULL((
SELECT TOP 1 TableA_ID
FROM TableA
WHERE ID = r.ID
AND Status <> 3
ORDER BY T_Date DESC
), 0)
ORDER BY T_Date ASC
Looks like you can use not exists rather than the sorts. I think you'll probably get a better performance boost by use a CTE or derived table instead of the a scalar subquery.
select *
from r ... left outer join
(
select ID, min(t_date) as min_date from TableA t1
where status = 3 and not exists (
select 1 from TableA t2
where t2.ID = t1.ID
and t2.status <> 3 and t2.t_date > t1.t_date
)
group by ID
) as md on md.ID = r.ID ...
or
select *
from r ... left outer join
(
select t1.ID, min(t1.t_date) as min_date
from TableA t1 left outer join TableA t2
on t2.ID = t1.ID and t2.status <> 3
where t1.status = 3 and t1.t_date < t2.t_date
group by t1.ID
having count(t2.ID) = 0
) as md on md.ID = r.ID ...
It also appears that you're relying on an identity column but it's not clear what those values mean. I'm basically ignoring it and using the date column instead.
Try this:
SELECT TOP 1 CONVERT( DATE, T_Date) AS T_Date
FROM TableA a1
LEFT JOIN (
SELECT ID, MAX(TableA_ID) AS MaxAID
FROM TableA
WHERE Status <> 3
GROUP BY ID
) a2 ON a2.ID = a1.ID AND a1.TableA_ID > coalesce(a2.MAXAID,0)
WHERE a1.ID = r.ID AND a1.Status = 3
ORDER BY T_Date ASC
The use of TOP 1 in combination with the unexplained r alias concern me. There's almost certainly a MUCH better way to get this data into your results that doesn't involve doing this in a sub query (unless this is for an APPLY operation).
I need to select the last record in the academic table which has two columns for date and time. When I run the query I get an error. Only one expression can be specified in the select list when the subquery is not introduced with EXISTS.
USE PCUnitTest
SELECT C.ACCOUNTNO, C.CONTACT, C.LASTNAME, C.KEY4, A.PEOPLE_ID, A.APP_STATUS, A.APP_DECISION, A.REVISION_DATE, A.REVISION_TIME
FROM ACADEMIC AS A INNER JOIN
GM.dbo.CONTACT1 AS C ON A.PEOPLE_ID = C.KEY4
WHERE A.REVISION_DATE = (SELECT TOP (1) REVISION_DATE, REVISION_TIME, PEOPLE_CODE, PEOPLE_ID, PEOPLE_CODE_ID, ACADEMIC_YEAR, ACADEMIC_TERM, ACADEMIC_SESSION, PROGRAM, DEGREE, CURRICULUM
FROM PCUnitTest.dbo.ACADEMIC
ORDER BY REVISION_DATE DESC, REVISION_TIME DESC)
You can Join the query you are using in the where
USE PowerCampusUnitTest
SELECT C.ACCOUNTNO, C.CONTACT, C.LASTNAME, C.KEY4, A.PEOPLE_ID, A.APP_STATUS, A.APP_DECISION, A.REVISION_DATE, A.REVISION_TIME
FROM ACADEMIC AS A
INNER JOIN GoldMineUnitTest.dbo.CONTACT1 AS C
ON A.PEOPLE_ID = C.KEY4
INNER JOIN (
SELECT TOP 1 A2.REVISION_DATE,A2.REVISION_TIME FROM PowerCampusUnitTest.dbo.ACADEMIC A2
ORDER BY REVISION_DATE DESC, REVISION_TIME DESC
)AS A2
ON A.REVISION_DATE = A2.REVISION_DATE AND A.REVISION_TIME = A2.REVISION_TIME
Use ROW_NUMBER()
USE PCUnitTest
SELECT
R.ACCOUNTNO, R.CONTACT, R.LASTNAME, R.KEY4, R.PEOPLE_ID, R.APP_STATUS, R.APP_DECISION, R.REVISION_DATE, R.REVISION_TIME
FROM
(
SELECT C.ACCOUNTNO, C.CONTACT, C.LASTNAME, C.KEY4, A.PEOPLE_ID, A.APP_STATUS, A.APP_DECISION, A.REVISION_DATE, A.REVISION_TIME
,ROW_NUMBER() OVER (ORDER BY A.REVISION_DATE DESC, A.REVISION_TIME DESC) RN
FROM ACADEMIC AS A INNER JOIN
GMUnitTest.dbo.CONTACT1 AS C ON A.PEOPLE_ID = C.KEY4
) R
WHERE RN=1
If you want to get the latest row for each PEOPLE_ID, then add PARTITION BY
SELECT
R.ACCOUNTNO, R.CONTACT, R.LASTNAME, R.KEY4, R.PEOPLE_ID, R.APP_STATUS, R.APP_DECISION, R.REVISION_DATE, R.REVISION_TIME
FROM
(
SELECT C.ACCOUNTNO, C.CONTACT, C.LASTNAME, C.KEY4, A.PEOPLE_ID, A.APP_STATUS, A.APP_DECISION, A.REVISION_DATE, A.REVISION_TIME
,ROW_NUMBER() OVER (PARTITION BY A.PEOPLE_ID ORDER BY A.REVISION_DATE DESC, A.REVISION_TIME DESC) RN
FROM ACADEMIC AS A INNER JOIN
GMUnitTest.dbo.CONTACT1 AS C ON A.PEOPLE_ID = C.KEY4
) R
WHERE RN=1
I am trying to use a correlated subquery, but I am trying to limit it to the "best" record. When I use SQL very similiar to what follows, I get two rows per BigTable.identifier, and I wish to have only one. In the 'UNION' statement, the second half is more desirable than the first half. However, sometimes the first half will be needed. Any ideas? Here's the code:
select
BigTable.identifier,
Correlated.ID,
Correlated.Effective_Date,
Correlated.Period_Number
from
BigTable
inner join
(
select
TOP 2147483647
Table3.identifier,
Table4.Effective_Date,
Table4.Period_Number
from
Table3
inner join Table4 on Table3.matching_key = Table4.matching_key
where
Table4.Period_Number = 0
order by Table4.Effective_Date desc
UNION
select
TOP 2147483647
Table3.Identifer,
Table4.Effective_Date,
Table4.Period_Number
from
Table3
inner join Table5 on Table3.matching-key = Table5.matching-key
inner join Table4 on Table5.key1 = Table4.key1 and
Table5.key2 = Table4.key2
where
Table4.period_number = 1
order by Table4.Effective_Date desc
) as Correlated
on BigTable.identifier = Correlated.identifier
If each sub-query in that UNION had some condition which EXCLUDED the row if it was less-preferred, you would never see the less-preferred rows in the UNION.
So, if each were to have a NOT EXISTS (.... a better row in the other side of the union ....), you would eliminate less-preferred rows at the root.
I'm not clear on how you want to use effective date. Assuming you mean that you prefer Period=1 but if the Effective date is less you prefer Period=0, then something like this might work.
select
BigTable.identifier,
Correlated.ID,
Correlated.Effective_Date,
Correlated.Period_Number
from
BigTable
inner join
(
select
TOP 2147483647
Table3.identifier,
Table4.Effective_Date,
Table4.Period_Number
from
Table3
inner join Table4 on Table3.matching_key = Table4.matching_key
where
Table4.Period_Number = 0
AND NOT EXISTS
(select 1
from Table5 T5 inner join Table4 T4
on T5.key1 = T4.key1 and T5.key2 = T4.key2
where Table3.matching-key = T5.matching-key
and (T4.Effective_Date >= Table4.Effective_Date and T4.Period_Number = 1)
)
order by Table4.Effective_Date desc
UNION
select
TOP 2147483647
Table3.Identifer,
Table4.Effective_Date,
Table4.Period_Number
from
Table3
inner join Table5 on Table3.matching-key = Table5.matching-key
inner join Table4 on Table5.key1 = Table4.key1 and
Table5.key2 = Table4.key2
where
Table4.period_number = 1
AND NOT EXISTS
(select 1
from Table4 T4
where Table3.matching-key = T4.matching-key
and (T4.Period_Number > 0)
and (T4.Effective_Date > Table4.Effective_Date and T4.Period_Number = 0)
)
order by Table4.Effective_Date desc
) as Correlated
on BigTable.identifier = Correlated.identifier