I'm trying to select the estimated hours of a row with the lowest date from a table.
SELECT prev_est_hrs
FROM ( SELECT MIN(change_date), prev_est_hrs
FROM task_history
WHERE task_id = 5
GROUP BY prev_est_hrs
);
However this is returning two rows, why? I thought MIN was supposed to return the lowest only?
Help much appreciated.
You have a GROUP BY clause. The MIN will return the minimum value in each group.
Also, you are only returning the group by value from the outer SELECT.
Mitch is right. One way to get the prev_est_hrs for the record with the earliest change_date, which seems to be what you're trying to find, is with an analytic function:
SELECT prev_est_hrs
FROM (
SELECT prev_est_hrs, ROW_NUMBER() OVER (ORDER BY change_date) AS rn
FROM task_history
WHERE task_id = 5
)
WHERE rn = 1;
You need to consider what should happen if you have two rows with the same date. This would pick one of them at random. If there is some other criteria you could use to break the tie you could add that to the order by clause. If you wanted all matching rows in that case you could use rank() instead; look at dense_rank() as well, they all have their place.
Use this query to do that:
SELECT max(prev_est_hrs) keep (dense_rank first order by change_date)
FROM task_history
WHERE task_id = 5;
Related
I have a table like this
and i want my output to look like this
I need to look at the ID and then take max created date and max completed date for that ID. There is also some cases where completed date is still empty so in that case i just need to look at the max created date. Im not sure how to tackle this, doing a group by doesnt account for my multiple scenarios
Use ROW_NUMBER:
WITH cte AS (
SELECT *, ROW_NUMBER() OVER (PARTITION BY QUOTE_NUMBER
ORDER BY WORKBOOK_CREATED_DATE DESC) rn
FROM yourTable
)
SELECT *
FROM yourTable
WHERE rn = 1;
In SQL Server, I am attempting to pull the second latest NOTE_ENTRY_DT_TIME (items highlighted in screenshot). With the query written below it still pulls the latest date (I believe it's because of the grouping but the grouping is required to join later). What is the best method to achieve this?
SELECT
hop.ACCOUNT_ID,
MAX(hop.NOTE_ENTRY_DT_TIME) AS latest_noteid
FROM
NOTES hop
WHERE
hop.GEN_YN IS NULL
AND hop.NOTE_ENTRY_DT_TIME < (SELECT MAX(hope.NOTE_ENTRY_DT_TIME)
FROM NOTES hope
WHERE hop.GEN_YN IS NULL)
GROUP BY
hop.ACCOUNT_ID
Data sample in the table:
One of the "easier" ways to get the Nth row in a group is to use a CTE and ROW_NUMBER:
WITH CTE AS(
SELECT Account_ID,
Note_Entry_Dt_Time,
ROW_NUMBER() OVER (PARTITION BY AccountID ORDER BY Note_Entry_Dt_Time DESC) AS RN
FROM dbo.YourTable)
SELECT Account_ID,
Note_Entry_Dt_Time
FROM CTE
WHERE RN = 2;
Of course, if an ACCOUNT_ID only has 1 row, then it will not be returned in the result set.
The OP's statement "The row will not always be 2." from the comments conflicts with their statement "I am attempting to pull the second latest NOTE_ENTRY_DT_TIME" in the question. At a best guess, this means that the OP has rows with the same date, that could be the "latest" date. If so, then would simply need to replace ROW_NUMBER with DENSE_RANK. Their sampple data, however, doesn't suggest this is the case.
You can use window functions:
select *
from (
select
n.*,
row_number() over(partition by account_id order by note_entry_dt_time desc) rn
from notes n
) t
where rn = 2
i am having table having 23 records , I am trying to get total count of record and last record also in single query. something like that
select count(*) ,(m order by createdDate) from music m ;
is there any way to pull this out only last record as well as total count in PostgreSQL.
This can be done using window functions
select *
from (
select m.*,
row_number() over (order by createddate desc) as rn,
count(*) over () as total_count
from music
) t
where rn = 1;
Another option would be to use a scalar sub-query and combine it with a limit clause:
select *,
(select count(*) from order_test.orders) as total_count
from music
order by createddate desc
limit 1;
Depending on the indexes, your memory configuration and the table definition might be faster then the two window functions.
No, it's not not possible to do what is being asked, sql does not function that way, the second you ask for a count () sql changes the level of your data to an aggregation. The only way to do what you are asking is to do a count() and order by in a separate query.
Another solution using windowing functions and no subquery:
SELECT DISTINCT count(*) OVER w, last_value(m) OVER w
FROM music m
WINDOW w AS (ORDER BY date DESC RANGE BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING);
The point here is that last_value applies on partitions defined by windows and not on groups defined by GROUP BY.
I did not perform any test but I suspect my solution to be the less effective amongst the three already posted. But it is also the closest to your example query so far.
I have a table of data and want to retrieve the penultimate record.
How is this done?
TABLE: results
-------
30
31
35
I need to get 31.
I've been trying with rownum but it doesn't seem to work.
Assuming you want the second highest number and there are no ties
SELECT results
FROM (SELECT results,
rank() over (order by results desc) rnk
FROM your_table_name)
WHERE rnk = 2
Depending on how you want to handle ties, you may want either the rank, dense_rank, or row_number analytic function. If there are two 35's for example, would you want 35 returned? Or 31? If there are two 31's, would you want a single row returned? Or would you want both 31's returned.
This can use for n th rank ##
select Total_amount from (select Total_amount, rank() over (order by Total_amount desc) Rank from tbl_booking)tbl_booking where Rank=3
I am creating an SP which gives some result by applying distinct on it, now I want to implement sever side paging, so I tried using Row_number on distinct result like:
WITH CTE AS
(
SELECT ROW_NUMBER() OVER(ORDER BY tblA.TeamName DESC)
as Row,tblA.TeamId,tblA.TeamName,tblA.CompId,tblA.CompName,tblA.Title,tblA.Thumbnail,tblA.Rank,tblA.CountryId,tblA.CountryName
FROM
(
--The table query starts with SELECT
)tblA
)
SELECT CTE.* FROM CTE
WHERE CTE.Row BETWEEN #StartRowIndex AND #StartRowIndex+#NumRows-1
ORDER BY CTE.CountryName
but rows are first assigned RowNumber then distinct get applied that is why I am getting duplicate values, how to get distinct rows first then get row numbers for the same.
Any solution on this? Am I missing something?
need answer ASAP.
thanks in advance!
Don't you need to add "partition by" to your ROW_NUMBER statement?
ROW_NUMBER() OVER(Partition by ___, ___, ORDER BY tblA.TeamName DESC)
In the blank spaces, place the column names you would like to create a new row number for. Duplicates will receive a number that is NOT 1 so you might not need the distinct.
To gather the unique values you could write a subquery where the stored procedure only grabs the rows with a 1 in them.
select * from
(
your code
) where row = 1
Hope that helps.
I'm not sure why you're doing this:
WHERE CTE.Row BETWEEN #StartRowIndex AND #StartRowIndex+#NumRows-1