I am looking to calculate the difference between the current & last Value organised by the timestamp column?
My table is organised as follows:
MeterID(PK,FK,int.not null), ActualTimeStamp(smalldatetime,not null), Value(float,null)
Meter ID ActualTimeStamp Value
312514 2013-01-01 08:08:00 72
312514 2013-01-01 08:07:00 12
So my answer should be 72 - 12 = 60
The only solutions I can seem to find are using Row Number which i dont have an option of, if anyone can assist id really apprecieate it as its busting my brain.
Here's a query that can help you. Just modify this to fit your need/table names/etc.
with sub as (
select meterid,
actualtimestamp,
value,
row_number() over (partition by meterid order by actualtimestamp desc) as rn
from test
)
select meterid,
actualtimestamp,
value,
value - isnull((select value
from sub
where s.meterid = meterid
and rn = s.rn + 1), value) as answer
from sub s
order by meterid, actualtimestamp desc;
Basically what it does is that it adds a row number using the row_number() aggregate function. Using the row number, the query tries to get the value from the previous entry and getting the value difference.
Try the fiddler here
In SQL Server 2008, I would recommend a outer applyhere the short code of find diff with your requirement
select t.*, isnull((t.value - tprev.value),0) as diff
from test t outer apply
(select top 1 tprev.*
from test tprev
where tprev.meterid = t.meterid and
tprev.actualtimestamp < t.actualtimestamp
order by tprev.actualtimestamp desc
)tprev
Related
please help me with the following problem. I have spent already one week trying to put all the logic into one SQL query but still got no elegant result. I hope the SQL experts could give me a hint,
I have a table which has 4 fields: date, expire_month, expire_year and value. The primary key is defined on 3 first fields. Thus for a concrete date few values are present with different expire_month, expire_year. I need to chose one value from them for every date, present in the table.
For example, when I execute a query:
SELECT date, expire_month, expire_year, value FROM futures
WHERE date = ‘1989-12-01' ORDER BY expire_year, expire_month;
I get a list of values for the same date sorted by expirity (months are coded with letters):
1989-12-01 Z 1989 408.25
1989-12-01 H 1990 408.25
1989-12-01 K 1990 389
1989-12-01 N 1990 359.75
1989-12-01 U 1990 364.5
1989-12-01 Z 1990 375
The correct single value for that date is the k-th record from top. For example, of k is 2 then the «correct single» record would be:
1989-12-01 H 1990 408.25
How can I select these «correct single» values for every date in my table?
You can do it with rank():
select t.date, t.expire_month, t.expire_year, t.value from (
select *,
rank() over(partition by date order by expire_year, expire_month) rn
from futures
) t
where t.rn = 2
The column rn in the subquery, is actually the rank of the row grouped by date. Change 2 to the rank you want.
While forpas's answer is the better one (Though I think I'd use row_number() instead of rank() here), window functions are fairly recent additions to Sqlite (In 3.25). If you're stuck on an old version and can't upgrade, here's an alternative:
SELECT date, expire_month, expire_year, value
FROM futures AS f
WHERE (date, expire_month, expire_year) =
(SELECT f2.date, f2.expire_month, f2.expire_year
FROM futures AS f2
WHERE f.date = f2.date
ORDER BY f2.expire_year, f2.expire_month
LIMIT 1 OFFSET 1)
ORDER BY date;
The OFFSET value is 1 less than the Kth row - so 1 for the second row, 2 for the third row, etc.
It executes a correlated subquery for every row in the table, though, which isn't ideal. Hopefully your composite primary key columns are in the order date, expire_year, expire_month, which will help a lot by eliminating the need for additional sorting in it.
You can try the following query.
select * from
(
SELECT rownum seq, date1, expire_month, expire_year, value FROM testtable
WHERE date1 = to_date('1989-12-01','yyyy-mm-dd')
ORDER BY expire_year, expire_month
)
where seq=2
I am trying to get a new column(computed) to assign points based on the positions in the positions column as in this image
I have tried this query below but my quest was not successful: I seek your assistance please help
query in sql server
You can't do rank using apply like that. You'll always get "1". Use a subquery:
select . . .
from (select ae.*, rank() over (order by averagemark desc) as position
from agriculturalentries
) cross join
(values (case when rank >= 13 then 150 - rank * 10 end) ) as v(pointsearned);
I find the arithmetic easier to type than your case, but you can use the more verbose form.
You might ask why rank() always returns "1" in your query. That is because apply only considers one row at a time (as written). The rank over that row is necessarily "1".
With AllMarks AS
(SELECT
CompetitorID,
ApiEntryId,
AverageMark,
RANK() OVER (ORDER BY AverageMark)AS RankPosition
-- Add other columns
FROM ApicultureEntries
)
SELECT
a.*,(CASE WHEN a.RankPosition < 14 THEN 150 - RankPosition * 10 ELSE NULL END) AS PositionEarned
FROM AllMarks AS a
I've looked around and found a few posts with LAG() and running total type queries, but none seem to fit what I'm looking for. Maybe i'm not using the correct terms in my search or maybe I might be over complicating the situation. Hope someone could help me out.
But what I'm looking to do is to take the previous result and multiple it by the current row for a range of dates. The starting is always some base number lets do 10 to keep it simple. The values will be float, but i kept it to round numbers here to better explain my inquiry.
The first is showing the calculation part and the 2nd table below is showing what the result should look like in the end.
date val1 calc_result
20120930 null 10
20121031 2 10*2=20
20121130 3 20*3=60
20121231 1 60*1=60
20130131 2 60*2=120
20130228 1 120*1=120
The query would return
20120930 10
20121031 20
20121130 60
20121231 60
20130131 120
20130228 120
I'm trying to see if this can be done in a query type solution or would a PL/SQL table/cursors need to be used?
Any help would be appreciated.
You can do this with a recursive CTE:
with dates as (
select t.*, row_number() over (order by date) as seqnum
from t
),
cte as (
select t.date, t.val, 10 as calc_result
from dates t
where t.seqnum = 1
union all
select t.date, t.val, cte.calc_result * t.val
from cte join
dates t
on t.seqnum = cte.seqnum + 1
)
select cte.date, cte.calc_result
from cte
order by cte.date;
This is calculating a cumulative product. You can do it with some exponential arithmetic. Replace 10 in the query with the desired start value.
select date,val1
,case when row_number() over(order by date) = 1 then 10 --set start value for first row
else 10*exp(sum(ln(val1)) over(order by date)) end as res
from tbl
My SQL experience is fairly minimal so please go easy on me here. I have a table tblForEx and I'm trying to create a query that looks at one particular column LastSalesRateChangeDate and also ForExRate.
Basically what I want to do is for the query to check that LastSalesRateChangeDate and then pull the ForExRate that is on the same line (obviously in the ForExRate column), then I need to check to see if there is a +/- 5% change since the last time the LastSalesRateChangeDate changed. I hope this makes sense, I tried to explain it as clearly as possible.
I believe I would need to create a 'subquery' to look at the LastSalesRateChangeDate and pull the ForEx rate from that date, but I just don't know how to go about this.
I should add this is being done in Access (SQL)
Sample data, here is what the table looks like:
| BaseCur | ForCur | ForExRate | LastSalesRateChangeDate
| USD | BRL | 1.718 | 12/9/2008
| USD | BRL | 1.65 | 11/8/2008
So I would need a query to look at the LastSalesRateChangeDate column, check to see if the date has changed, if so take the ForExRate value and then give a percentage difference of that ForExRate value since the last record.
So the final result would likely look like
"BaseCur" "ForCur" "Percentage Change since Last Sales Rate Change"
USD BRL X%
Gordon's answer pointed in the right direction:
SELECT t2.*, (SELECT top 1 t.ForExRate
FROM tblForEx t
where t.BaseCur=t2.BaseCur AND t.ForCur=t2.ForCur and t.LastSalesRateChangeDate<t2.LastSalesRateChangeDate
order by t.LastSalesRateChangeDate DESC, t.ForExRate DESC
) AS PreviousRate, [ForExRate]/[PreviousRate]-1 AS ChangeRatio
FROM tblForEx AS t2;
Access gives errors where the TOP 1 in the subquery causes "ties". We broke the ties and therefore removed the error by adding an extra item to the ORDER BY clause. To get the ratio to display as a percentage, switch to the design view and change the properties of that column accordingly.
If I understand correctly, you want the previous value. In MS Access, you can use a correlated subquery:
select t.*,
(select top (1) t2.LastSalesRateChangeDate
from tblForEx as t2
where t2.BaseCur = t.BaseCur and t2.ForCur = t.ForCur
t2.LastSalesRateChangeDate < t.LastSalesRateChangeDate
order by t2.LastSalesRateChangeDate desc
) as prev_LastSalesRateChangeDate
from t;
Now, with this as a subquery, you can get the previous exchange rate using a join:
select t.*, ( (t.ForExRate / tprev.ForExRate) - 1) as change_ratio
from (select t.*,
(select top (1) t2.LastSalesRateChangeDate
from tblForEx as t2
where t2.BaseCur = t.BaseCur and t2.ForCur = t.ForCur
t2.LastSalesRateChangeDate < t.LastSalesRateChangeDate
order by t2.LastSalesRateChangeDate desc
) as prev_LastSalesRateChangeDate
from t
) as t inner join
tblForEx as tprev
on tprev.BaseCur = t.BaseCur and tprev.ForCur = t.ForCur
tprev.LastSalesRateChangeDate = t.prev_LastSalesRateChangeDate;
As per my understanding, you can use LEAD function to get last changed date Rate in a new column by using below query:
WITH CTE AS (
SELECT *, LEAD(ForExRate, 1) OVER(PARTITION BY BaseCur, ForCur ORDER BY LastChangeDate DESC) LastValue
FROM #TT
)
SELECT BaseCur, ForCur, ForExRate, LastChangeDate , CAST( ((ForExRate - ISNULL(LastValue, 0))/LastValue)*100 AS float)
FROM CTE
Problem here is:
for every last row in group by you will have new calculalted column which we have made using LEAD function.
If there is only a single row for a particular BaseCur and ForCur, then also you will have NULL in column.
Resolution:
If you are sure that there will be at least two rows for each BaseCur and ForCur, then you can use WHERE clause to remove NULL values in final result.
WITH CTE AS (
SELECT *, LEAD(ForExRate, 1) OVER(PARTITION BY BaseCur, ForCur ORDER BY LastChangeDate DESC) LastValue
FROM #TT
)
SELECT BaseCur, ForCur, ForExRate, LastChangeDate , CAST( ((ForExRate - ISNULL(LastValue, 0))/LastValue)*100 AS float) Percentage
FROM CTE
WHERE LastValue IS NOT NULL
SELECT basetbl.BaseCur, basetbl.ForCur, basetbl.NewDate, basetbl.OldDate, num2.ForExRate/num1.ForExRate*100 AS PercentChange FROM
(((SELECT t.BaseCur, t.ForCur, MAX(t.LastSalesRateChangeDate) AS NewDate, summary.Last_Date AS OldDate
FROM (tblForEx AS t
LEFT JOIN (SELECT TOP 2 BaseCur, ForCur, MAX(LastSalesRateChangeDate) AS Last_Date FROM tblForEx AS t1
WHERE LastSalesRateChangeDate <>
(SELECT MAX(LastSalesRateChangeDate) FROM tblForEx t2 WHERE t2.BaseCur = t1.BaseCur AND t2.ForCur = t1.ForCur)
GROUP BY BaseCur, ForCur) AS summary
ON summary.ForCur = t.ForCur AND summary.BaseCur = t.BaseCur)
GROUP BY t.BaseCur, t.ForCur, summary.Last_Date) basetbl
LEFT JOIN tblForEx num1 ON num1.BaseCur=basetbl.BaseCur AND num1.ForCur = basetbl.ForCur AND num1.LastSalesRateChangeDate = basetbl.OldDate))
LEFT JOIN tblForEx num2 ON num2.BaseCur=basetbl.BaseCur AND num2.ForCur = basetbl.ForCur AND num2.LastSalesRateChangeDate = basetbl.NewDate;
This uses a series of subqueries. First, you are selecting the most recent date for the BaseCur and ForCur. Then, you are joining onto that the previous date. I do that by using another subquery to select the top two dates, and exclude the one that is equal to the previously established most recent date. This is the "summary" subquery.
Then, you get the BaseCur, ForCur, NewDate, and OldDate in the "basetbl" subquery. After that, it is two simple joins of the original table back onto those dates to get the rate that was applicable then.
Finally, you are selecting your BaseCur, ForCur, and whatever formula you want to use to calculate the rate change. I used a simple ratio in that one, but it is easy to change. You can remove the dates in the first line if you want, they are there solely as a reference point.
It doesn't look pretty, but complicated Access SQL queries never do.
I have a query:
;with date_cte as(
SELECT r.starburst_dept_name,r.monthly_past_date as PrevDate,x.monthly_past_date as CurrDate,r.starburst_dept_average - x.starburst_dept_average as Average
FROM
(
SELECT *,ROW_NUMBER() OVER(PARTITION BY starburst_dept_name ORDER BY monthly_past_date) AS rowid
FROM intranet.dbo.cse_reports_month
) r
JOIN
(
SELECT *,ROW_NUMBER() OVER(PARTITION BY starburst_dept_name ORDER BY monthly_past_date) AS rowid
FROM intranet.dbo.cse_reports_month
Where month(monthly_past_date) > month(DATEADD(m,-2,monthly_past_date))
) x
ON r.starburst_dept_name = x.starburst_dept_name AND r.rowid = x.rowid+1
Where r.starburst_dept_name is NOT NULL
)
Select *
From date_cte
Order by Average DESC
So doing some testing, I have alter some columns data, to see why it gives me certain information. I don't know why when I run the query it gives my a date column that should not be there from "january" (row 4) like the picture below:
The database has more data that has the same exact date '2014-01-25 00:00:00.000', so I'm not sure why it would only get that row and compare the average?
I did before I run the query alter the column in that row and change the date? But I'm not sure if that would have something to do with it.
UPDATE:
I have added the sqlfinddle,
What I would like to get it subtract the average
from last_month - last 2 month ago.
It Was actually working until I made a change and alter the data.
I made the changes to test a certain situation, which obviously lead
to learning that there are flaws to the query.
Based on your SQL Fiddle, this eliminates joins from prior than month-2 from showing up.
SELECT
thismonth.starburst_dept_name
,lastmonth.monthtly_past_date [PrevDate]
,thismonth.monthtly_past_date [CurrDate]
,thismonth.starburst_dept_average - lastmonth.starburst_dept_average as Average
FROM dbo.cse_reports thismonth
inner join dbo.cse_reports lastmonth on
thismonth.starburst_dept_name = lastmonth.starburst_dept_name
AND month(DATEADD(MONTH,-1,thismonth.monthtly_past_date))=month(lastmonth.monthtly_past_date)
WHERE MONTH(thismonth.monthtly_past_date)=month(DATEADD(MONTH,-1,GETDATE()))
Order by thismonth.starburst_dept_average - lastmonth.starburst_dept_average DESC