I have audit data captured over time points which I would like to aggregate up to display where the value was the same over a period of time using SQL Server 2014.
Taking the below example data
I would like to transpose it to this ideally without using a cursor - you will see that the output is recording the time period where the value is the same and as such, the same value can be repeated over different periods (seen in rows 3 and 6).
I have been looking at LEAD() and LAG() as potential solutions, however I cannot fathom out how to make this work in order to band by time for the same value
Any direction would be gratefully received
In case the column [value] doesnt contain distinct number, you can use this query
SELECT start,end,value
FROM (SELECT MIN(ts) start
,MAX(ts) end
,value
,C
FROM (SELECT ts
,value
,(ROW_NUMBER() OVER (ORDER BY ts)
- ROW_NUMBER() OVER (PARTITION BY value ORDER BY ts)) C
FROM YourTable) x
GROUP BY value,C) y ORDER BY start
After seeing your further comments, the below is obviously of no use...
I think you may be over complicating it. If you are looking for the minimum and maximum ts per distinct value, then you can just use MIN & MAX and group by the Value, e.g.
SELECT MIN(ts) AS [Start] ,
MAX(ts) AS [End] ,
Value
FROM Table
GROUP BY Value
Related
I'm fairly new to Microsoft SQL Server, so maybe this is very simple yet I just don't have the experience to pull from.
The data I have is similar to the first three columns shown (A, B, C). I want to use those columns to return the data in the yellow highlighted column (D). Basically, I'm trying to show all values of a variable from the current week onward, including when there are change points of the variable. The value of the variable should continue forward in time until the value of the variable changes (column C).
Thanks in advance.
SELECT T1.*, COALESCE(SQ.NewValue, T1.StartingValue) FROM YourTable T1
OUTER APPLY (SELECT TOP 1 T2.NewValue FROM YourTable T2
WHERE T1.Week <= T2.week AND
T2.NewValue IS NOT NULL
ORDER BY T2.Week DESC) SQ
One way is to make Column D a correlated sub-query that gets the most recent previous value of C that is not NULL.
One method, which doesn't need 2 table scans is to use a CTE to create a "group number" and then the OVER clause with a MAX:
WITH VTE AS (
SELECT *
FROM (VALUES(1,0.5,NULL),
(2,0.5,1),
(3,0.5,NULL),
(4,0.5,NULL),
(5,0.5,0.8),
(6,0.5,NULL)) V(WeekNo, Starting, New)),
CTE AS(
SELECT *,
COUNT(New) OVER (ORDER BY WeekNo ASC ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) AS Grp
FROM VTE)
SELECT WeekNo, Starting, New,
ISNULL(MAX(New) OVER (PARTITION BY CTE.Grp),Starting) AS Result
FROM CTE
ORDER BY WeekNo;
I have some sample data as follows
Name Value Timestamp
a 23 2016/12/23 11:23
a 43 2016/12/23 12:55
b 12 2016/12/23 12:55
I want to select the latest value for a and b. When I used Last_Value, I used the following query
Select Name, Last_Value(Value) over (partition by Name order by timestamp) from table
This returned 2 rows for a, but I wanted it grouped so that I get only the last entered value for each name. So I had to use sub queries.
select x.Name,x.Value from (Select Name, Last_Value(Value) over (partition by Name order by timestamp) ) as x group by x.Name,x.Value
This again returns 2 records for a...I just wanted to do a group by and orderby and instaed of selelcting the max() wanted to select the top record.
Can anybody tell me how to solve this problem?
One method doesn't use window functions:
select t.*
from table t
where t.timestamp = (select max(t2.timestamp) from table t2 where t2.name = t.name);
Otherwise, the subquery method is fine, although I would often use row_number() and conditional aggregation rather than last_value() (or first_value() with a descending order by).
Unfortunately, SQL Server does not support first_value() or last_value() as an aggregation function, only as a window function.
I need some help to create a new column in a database in SQL Server 2008.
I have the following data table
Please have a look at a snapshot of my table
Table
In the blank column I would like to put the difference between the current status date and the next status' date. And for the last ID_Status for each ID_Ticket I would like to have the difference between now date and it's date !
I hope that you got an idea about my problem.
Please share if you have any ideas about how to do .
Many thanks
kind regards
You didn't specify your RDBMS, so I'll post an answer for both since they are almost identical :
SQL-Server :
SELECT ss.id_ticket,ss.id_status,ss.date_status,
DATEDIFF(day,ss.date_status,ss.coalesce(ss.next_date,GETDATE())) as diffStatus
FROM (
SELECT t.*,
(SELECT TOP 1 s.date_status FROM YourTable s
WHERE t.id_ticket = s.id_ticket and s.date_status > t.date_status
ORDER BY s.date_status ASC) as next_date)
FROM YourTable t) ss
MySQL :
SELECT ss.id_ticket,ss.id_status,ss.date_status,
DATEDIFF(ss.date_status,ss.coalesce(ss.next_date,now())) as diffStatus
FROM (
SELECT t.*,
(SELECT s.date_status FROM YourTable s
WHERE t.id_ticket = s.id_ticket and s.date_status > t.date_status
ORDER BY s.date_status ASC limit 1) as next_date)
FROM YourTable t) ss
This basically first use a correlated sub query to bring the next date using limit/top , and then wrap it with another select to calculate the difference between them using DATEDIFF().
Basically it can be done without the wrapping query, but it won't be readable since the correlated query will be inside the DATEDIFF() function, so I prefer this way.
I'm trying to use an input parameter to specify a number of rows in a window function in SQL Server 2014 Standard, but am getting an error because it's expecting an actual integer value. It would be ideal to parameterize the procedure because different ranges of non-contiguous days are needed for a moving average calculation. A simple, general example would be:
CREATE PROCEDURE dbo.MovingAverage #days INTEGER
AS
SELECT
saledate,
item,
saleprice,
CASE WHEN ROW_NUMBER() OVER (PARTITION BY item ORDER BY saledate) > #days
THEN AVG(saleprice) OVER (PARTITION BY item ORDER BY saledate ROWS BETWEEN #days PRECEDING AND 1 PRECEDING)
ELSE NULL END [MA]
FROM transactions
I could brute force a solution but am curious if I'm missing something to keep it simple. Any ideas?
I'm try to select a certain rows from my table using the row_number over. However, the sql will prompt the error msg "Invalid column name 'ROWNUMBERS' ". Anyone can correct me?
SELECT ROW_NUMBER() OVER (ORDER BY Price ASC) AS ROWNUMBERS, *
FROM Product
WHERE ROWNUMBERS BETWEEN #fromCount AND #toCount
Attempting to reference the aliased column in the WHERE clause does not work because of the logical query processing taking place. The WHERE is evaluated before the SELECT clause. Therefore, the column ROWNUMBERS does not exist when WHERE is evaluated.
The correct way to reference the column in this example would be:
SELECT a.*
FROM
(SELECT ROW_NUMBER() OVER (ORDER BY Price ASC) AS ROWNUMBERS, *
FROM Product) a
WHERE a.ROWNUMBERS BETWEEN #fromCount AND #toCount
For your reference, the order for operations is:
FROM
WHERE
GROUP BY
HAVING
SELECT
ORDER BY
There is another answer here that solves the specific error reported. However, I also want to address the wider problem. It looks a lot like what you are doing here is paging your results for display. If that is the case, and if you can use Sql Server 2012, there is a better way now. Take a look at OFFSET/FETCH:
SELECT First Name + ' ' + Last Name
FROM Employees
ORDER BY First Name
OFFSET 10 ROWS FETCH NEXT 5 ROWS ONLY;
That would show the third page of a query where the page size is 5.