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Get the Max value of each group in SQL
Posted on 2012-12-26
In SQL, How to get the Maximum value of each group.
In my Syntax, I have a column name : FileCount which counts number of records for each FileName.
My output could be like this..
FileName FileCount
ABC 1
ABC 2
ABC 3
DEF 1
So, expected results are
FileName FileCount
ABC 3
DEF 1
Below is my current syntax ..
In my Syntax, I have a column name : FileCount which counts number of records for each FileName.
My output could be like this..
FileName FileCount
ABC 1
ABC 2
ABC 3
DEF 1
So, expected results are
FileName FileCount
ABC 3
DEF 1
Below is my current syntax ..
With CTE
As
(
select
[FileName],
[Trade Name],
[Invoice Number],
[Invoice Date]
,ROW_NUMBER() OVER(PARTITION BY [FileName] ORDER BY [FileName] ASC) AS FileCount
from PlacedOrderDetails
where CreatedDate >= '12/21/2012'
)
select
[FileName],
[Trade Name],
[Invoice Number],
[Invoice Date]
From CTE
[X]
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19 Comments
It looks like you're trying to count the file names. You can get there with this:
SELECT [FileName], count(*) as [FileCount]
FROM PlacedOrderDetails
WHERE CreatedDate >= '12/21/2012'
GROUP BY [FileName]
SELECT [FileName], count(*) as [FileCount]
FROM PlacedOrderDetails
WHERE CreatedDate >= '12/21/2012'
GROUP BY [FileName]
Active 4 days ago
FileName FileCount
ABC 1
ABC 2
ABC 3
DEF 1
GHI 1
GHI 2
So, expected results are
FileName FileCount
ABC 3
DEF 1
GHI 2
ABC 1
ABC 2
ABC 3
DEF 1
GHI 1
GHI 2
So, expected results are
FileName FileCount
ABC 3
DEF 1
GHI 2
please check this article:
http://www.experts-exchange.com/Database/Miscellaneous/A_3203-DISTINCT-vs-GROUP-BY-and-why-does-it-not-work-for-my-query.html
it explains exactly how to do this
http://www.experts-exchange.com/Database/Miscellaneous/A_3203-DISTINCT-vs-GROUP-BY-and-why-does-it-not-work-for-my-query.html
it explains exactly how to do this
To find the max value, this should do the trick
SELECT [FileName], Max(FileCount) as [FileCount]
FROM PlacedOrderDetails
WHERE CreatedDate >= '12/21/2012'
GROUP BY [FileName]
SELECT [FileName], Max(FileCount) as [FileCount]
FROM PlacedOrderDetails
WHERE CreatedDate >= '12/21/2012'
GROUP BY [FileName]
Active 4 days ago
@sjwales
I tried your query in the very first attempt, before posting over here.
I have around 8 - 9 columns
Group by expect all the columns to be mentioned.
On doing so, we don't get the MAX (FileCount)
I tried your query in the very first attempt, before posting over here.
I have around 8 - 9 columns
Group by expect all the columns to be mentioned.
On doing so, we don't get the MAX (FileCount)
chokka, did you try the code I posted?
It will work without the cte, and should give you the max file count (by way of counting all the files with the same name).
If I've misunderstood your problem, my apologies.
It will work without the cte, and should give you the max file count (by way of counting all the files with the same name).
If I've misunderstood your problem, my apologies.
Is FileCount unique for each occurrence of FileName ? If so this might work:
Even if it's not unique you could change
Select othercol1, othercol2, otherco3, FileName, FileCount
to
Select DISTINCT othercol1, othercol2, otherco3, FileName, FileCount
Would that work ?
Select othercol1, othercol2, otherco3, FileName, FileCount
from
(
SELECT [FileName], Max(FileCount) as [FileCount]
FROM PlacedOrderDetails
WHERE CreatedDate >= '12/21/2012'
GROUP BY [FileName]
) as a
join PlacedOrderDetails b on a.FileName = b.FileName and a.FileCount = b.FileCount
Even if it's not unique you could change
Select othercol1, othercol2, otherco3, FileName, FileCount
to
Select DISTINCT othercol1, othercol2, otherco3, FileName, FileCount
Would that work ?
Active today
You are correct, you have to enumerate any column not part of an aggregate (min, max, sum, avg, count) in GROUP BY.
That makes sense, because the DBMS cannot decide what you want to see as single values if you have not included them in the GROUP BY. You can for example decide to use the minimum of each other column:
So, you will need to define exactly what result you want to get, including the other columns.
That makes sense, because the DBMS cannot decide what you want to see as single values if you have not included them in the GROUP BY. You can for example decide to use the minimum of each other column:
select FileName, min([Trade Name]), min([Invoice Number]), min([Invoice Date]), max(FileCount)
from PlacedOrderDetails
where CreatedDate >= '12/21/2012'
So, you will need to define exactly what result you want to get, including the other columns.
Active 4 days ago
For all the experts for your query suggestion,
Group by is expecting all the columns which i mentioning in the select query.
On providing all the columns in the Group by, i am not able to get the generated value !!
Group by is expecting all the columns which i mentioning in the select query.
On providing all the columns in the Group by, i am not able to get the generated value !!
this will do (as by my article), based on your code:
With CTE
As
(
select
[FileName],
[Trade Name],
[Invoice Number],
[Invoice Date]
,ROW_NUMBER() OVER(PARTITION BY [FileName] ORDER BY [Invoice Date] ASC) AS FileCount
,ROW_NUMBER() OVER(PARTITION BY [FileName] ORDER BY [Invoice Date] DESC) AS rn
from PlacedOrderDetails
where CreatedDate >= '12/21/2012'
)
select
[FileName],
[Trade Name],
[Invoice Number],
[Invoice Date]
From CTE
WHERE rn = 1
Active 3 days ago
Can you provide some sample data and the expected output? I suspect the solution will utilize a window function such as row_number() as you have shown in your cte expression, but such functions also include count() and max() which might better provide a solution.
Active 4 days ago
@angelIII
select
[FileName],
[Trade Name],
[Invoice Number],
[Invoice Date]
From CTE
We are missing the FileCount.
I included, but FileCount reflected as FileCount= 1.
We need MAX(FileCount)
select
[FileName],
[Trade Name],
[Invoice Number],
[Invoice Date]
From CTE
We are missing the FileCount.
I included, but FileCount reflected as FileCount= 1.
We need MAX(FileCount)
I don't believe what your trying to do is uncommon or complicated. There seems to be some communication trouble.
Please try this and see if it is any closer to your desired results.
SELECT
[FileName],
[Trade Name],
[Invoice Number],
[Invoice Date],
(SELECT count(*) FROM PlacedOrderDetails O WHERE P.[FileName] = O.[FileName]) as [FileCount]
FROM PlacedOrderDetails P
WHERE CreatedDate >= '12/21/2012'
Please try this and see if it is any closer to your desired results.
SELECT
[FileName],
[Trade Name],
[Invoice Number],
[Invoice Date],
(SELECT count(*) FROM PlacedOrderDetails O WHERE P.[FileName] = O.[FileName]) as [FileCount]
FROM PlacedOrderDetails P
WHERE CreatedDate >= '12/21/2012'
Active 4 days ago
Thank you for helping.
Sounds simple, but it is complicated.
I have attached the spreadsheet with sample data and expected output.
Hope this will help me as well as experts can bring new query logic !!
ExpectedOutput.xls
Sounds simple, but it is complicated.
I have attached the spreadsheet with sample data and expected output.
Hope this will help me as well as experts can bring new query logic !!
ExpectedOutput.xls
Using your sample data to create a variable table called @temp:
Either of these queries works:
You can substitute your CTE name and it should work.
Unless there is some reason to use a CTE that isn't discussed here, you can accomplish your goal more efficiently without it by just querying the PlacedOrderDetails table directly.
I believe that syntax would be
declare @temp as table (FileName varchar(50), [Trade Name] varchar(25), [Invoice Number] varchar(10), [Invoice Date] datetime, FileCount int)
insert into @temp values ('A176998 12-11-2012.csv', 'ENALAPRIL', '176998', '11/01/2012', 1)
insert into @temp values ('A176998 12-11-2012.csv', 'SENNA PLUS', '176998', '11/01/2012', 2)
insert into @temp values ('B176999 12-11-2012.csv', 'SENNA PLUS', '176999', '11/15/2012', 1)
insert into @temp values ('C5043379 11-29-2012.csv', 'ADVAIR DISKUS', '5043379', '12/02/2012', 1)
insert into @temp values ('C5043379 11-29-2012.csv', 'ASMANEX 30INHL', '5043379', '12/02/2012', 2)
insert into @temp values ('C504337911-29-2012.csv', 'ATRIPLA', '5043379', '12/02/2012', 3)
insert into @temp values ('C5043379 11-29-2012.csv', 'BENICAR', '5043379', '12/02/2012', 4)
Either of these queries works:
SELECT
DISTINCT FileName, [Invoice Number], [Invoice Date],
(SELECT max([FileCount]) FROM @temp b WHERE b.FileName = a.FileName) as FileCount
FROM @temp a
SELECT FileName, [Invoice Number], [Invoice Date], max([FileCount]) as FileCount
FROM @temp
GROUP BY FileName, [Invoice Number], [Invoice Date]
You can substitute your CTE name and it should work.
Unless there is some reason to use a CTE that isn't discussed here, you can accomplish your goal more efficiently without it by just querying the PlacedOrderDetails table directly.
I believe that syntax would be
SELECT
DISTINCT [FileName],
[Trade Name],
[Invoice Number],
[Invoice Date],
(SELECT count(*) FROM PlacedOrderDetails O WHERE P.[FileName] = O.[FileName]) as [FileCount]
FROM PlacedOrderDetails P
WHERE CreatedDate >= '12/21/2012'
Active 3 days ago
with cte as
(SELECT
[FileName],
[Trade Name],
[Invoice Number],
[Invoice Date],
count([FileName]) over (partition by [FileName] order by [FileName]) as [FileCount],
row_number() over (partition by [FileName], [Invoice Date] order by [Trade Name] desc)as rn
FROM PlacedOrderDetails)
SELECT
[FileName],
[Trade Name],
[Invoice Number],
[Invoice Date],
[FileCount]
from cte
where rn = 1;
(SELECT
[FileName],
[Trade Name],
[Invoice Number],
[Invoice Date],
count([FileName]) over (partition by [FileName] order by [FileName]) as [FileCount],
row_number() over (partition by [FileName], [Invoice Date] order by [Trade Name] desc)as rn
FROM PlacedOrderDetails)
SELECT
[FileName],
[Trade Name],
[Invoice Number],
[Invoice Date],
[FileCount]
from cte
where rn = 1;
Active 3 days ago
I omitted the CreatedDate since your example did not show it and none of the invoice dates were greater than or equal to 12/21/2012, but it can easily be included in the common table expression.
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