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
Related
We created a view in Postgres and I am getting strange result.
View Name: event_puchase_product_overview
When I try to get records with *, I get the correct result. but when I try to get specific fields, I get wrong values.
I hope the screens attached here can explain the problem well.
select *
from event_purchase_product_overview
where id = 15065;
select id, departure_id
from event_puchase_product_overview
where id = 15065;
VIEW definition:
CREATE OR REPLACE VIEW public.event_puchase_product_overview AS
SELECT row_number() OVER () AS id,
e.id AS departure_id,
e.type AS event_type,
e.name,
p.id AS product_id,
pc.name AS product_type,
product_date.attribute AS option,
p.upcomming_date AS supply_date,
pr.date_end AS bid_deadline,
CASE
WHEN (pt.categ_id IN ( SELECT unnest(tt.category_ids) AS unnest
FROM ( SELECT string_to_array(btrim(ir_config_parameter.value, '[]'::text), ', '::text)::integer[] AS category_ids
FROM ir_config_parameter
WHERE ir_config_parameter.key::text = 'trip_product_flight.product_category_hotel'::text) tt)) THEN e.maximum_rooms
WHEN (pt.categ_id IN ( SELECT unnest(tt.category_ids) AS unnest
FROM ( SELECT string_to_array(btrim(ir_config_parameter.value, '[]'::text), ', '::text)::integer[] AS category_ids
FROM ir_config_parameter
WHERE ir_config_parameter.key::text = 'trip_product_flight.product_category_flight'::text) tt)) THEN e.maximum_seats
WHEN (pt.categ_id IN ( SELECT unnest(tt.category_ids) AS unnest
FROM ( SELECT string_to_array(btrim(ir_config_parameter.value, '[]'::text), ', '::text)::integer[] AS category_ids
FROM ir_config_parameter
WHERE ir_config_parameter.key::text = 'trip_product_flight.product_category_bike'::text) tt)) THEN e.maximum_bikes
ELSE e.maximum_seats
END AS departure_qty,
CASE
WHEN now()::date > pr.date_end AND po.state::text = 'draft'::text THEN true
ELSE false
END AS is_deadline,
pl.product_qty::integer AS purchased_qty,
pl.comments,
pl.price_unit AS unit_price,
rp.id AS supplier,
po.id AS po_ref,
po.state AS po_state,
po.date_order AS po_date,
po.user_id AS operator,
pl.po_state_line AS line_status
FROM event_event e
LEFT JOIN product_product p ON p.related_departure = e.id
LEFT JOIN product_template pt ON pt.id = p.product_tmpl_id
LEFT JOIN product_category pc ON pc.id = pt.categ_id
LEFT JOIN purchase_order_line pl ON pl.product_id = p.id
LEFT JOIN purchase_order po ON po.id = pl.order_id
LEFT JOIN purchase_order_purchase_requisition_rel prr ON prr.purchase_order_id = po.id
LEFT JOIN purchase_requisition pr ON pr.id = prr.purchase_requisition_id
LEFT JOIN res_partner rp ON rp.id = po.partner_id
LEFT JOIN ( SELECT p_1.id AS product_id,
pav.name AS attribute
FROM product_product p_1
LEFT JOIN product_attribute_value_product_product_rel pa ON pa.prod_id = p_1.id
LEFT JOIN product_attribute_value pav ON pav.id = pa.att_id
LEFT JOIN product_attribute pat ON pat.id = pav.attribute_id
WHERE pat.name::text <> ALL (ARRAY['Date'::character varying, 'Departure'::character varying]::text[])) product_date ON product_date.product_id = p.id
WHERE (p.id IN ( SELECT DISTINCT mrp_bom_line.product_id
FROM mrp_bom_line)) AND p.active
ORDER BY e.id, pt.categ_id, p.id;
If I add new event_event or new product_product I'll get a new definition of row_number in my view, then the column ID of my view is not stable.
at least you can't use row_number as Id of the view,
If you insist to use row_number, you can use the Order By "creation DATE" by this way all new records will be as last lines in the view and this will not change the correspondency between ID (row_number) and other columns.
Hope that helps !
Very likely the execution plan of your query depends on the columns you select. Compare the execution plans!
Your id is generated using the row_number window function. Now window functions are executed before the ORDER BY clause, so the order will depend on the execution plan and hence on the columns you select.
Using row_number without an explicit ordering doesn't make any sense.
To fix that, don't use
row_number() OVER ()
but
row_number() OVER (ORDER BY e.id, pt.categ_id, p.id)
so that you have a reliable ordering.
In addition, you should omit the ORDER BY clause at the end.
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
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
I'm tring to grab all fields from the latest Cash record, and then all fields from the related TransactionInfo record. I can't quite get this to work yet:
select t.*, top 1 c.* from Cash c
inner join TransactionInfo t
on c.TransactionID = t.id
order by c.createdOn desc
select top 1 *
from Cash c
inner join TransactionInfo t on c.TransactionID = t.id
order by createdOn desc
What's that top 1 doing there? If you only want one row then the TOP(1) must come first:
SELECT TOP(1) t.*, c.*
FROM Cash c
INNER JOIN TransactionInfo t
ON c.TransactionID = t.id
ORDER BY c.createdOn DESC
select t.,c.
from (Select top 1 * from Cash order by createdOn desc
) c
inner join TransactionInfo t
on c.TransactionID = t.id
order by createdOn desc
DOn;t use select * especially with a join, it wastes server resources.
SELECT c.*, t.* FROM cash c, transactioninfo t
WHERE c.infoid = t.id AND c.createdOn = (SELECT max(createdOn) FROM cash WHERE infoId = t.id) ORDER BY transactiontabledate desc
You need to find the record with the latest date from the cash table for each transactionId and use that also to filter it out in your query.