SQL Group By Problem - sql

Question

I have a table that has 3 cols namely points, project_id and creation_date. every time points are assigned a new record has been made, for example.
points = 20 project_id = 441 creation_date = 04/02/2011 -> Is one record
points = 10 project_id = 600 creation_date = 04/02/2011 -> Is another record
points = 5 project_id = 441 creation_dae = 06/02/2011 -> Is final record
(creation_date is the date on which record is entered and it is achieved by setting the default value to GETDATE())
now the problem is I want to get MAX points grouped by project_id but I also want creation_date to appear with it so I can use it for another purpose, if creation date is repeating its ok and I cannot group by creation_date because if I do so it will skip the points of project with id 600 and its wrong because id 600 is a different project and its only max points are 10 so it should be listed and its only possible if I do the grouping using project_id but then how should I also list creation_date
So far I am using this query to get MAX points of each project
SELECT MAX(points) AS points, project_id
FROM LogiCpsLogs AS LCL
WHERE (writer_id = #writer_id) AND (DATENAME(mm, GETDATE()) = DATENAME(mm, creation_date)) AND (points <> 0)
GROUP BY project_id
writer_id is the ID of writer whose points I want to see, like writer_id = 1, 2 or 3.
This query brings the result of current month only but I would like to list creation_date as well. Please help.

Answer 1

The subquery way
SELECT P.Project_ID, P.Creation_Date, T.Max_Points
FROM Projects P INNER JOIN
(
SELECT Project_ID, MAX(Points) AS Max_Points
FROM Projects
GROUP BY Project_ID
) T
ON P.Project_ID = T.Project_ID
AND P.Points = T.Max_Points
Please see comment: this will give you ALL days where max-points was achieved. If you only just want one, the query will be more complex.
Edits:
Misread requirements. Added additional constraint.

Answer 2

I'll give you sample..
SELECT MAX(POINTS),
PROJECT_ID,
CREATION_DATE
FROM yourtable
GROUP by CREATION_DATE,PROJECT_ID;

Answer 3

This should be what you want, you don't even need a group by or aggravate functions:
SELECT points, project_id, created_date
FROM #T AS LCL
WHERE writer_id = #writer_id AND points <> 0
AND NOT EXISTS (
SELECT TOP 1 1
FROM #T AS T2
WHERE T2.writer_id = #writer_id
AND T2.project_id = LCL.project_id
AND T2.points > LCL.points)
Where #T is your table, also if you want to only show the records where they were the total in general and not the total for just this given #writer_id then remove the restriction T2.writer_id = #writer_id from the inner query
And my code that I used to test:
DECLARE #T TABLE
(
writer_id int,
points int,
project_id int,
created_date datetime
)
INSERT INTO #T VALUES(1, 20, 441, CAST('20110204' AS DATETIME))
INSERT INTO #T VALUES(1, 10, 600, CAST('20110204' AS DATETIME))
INSERT INTO #T VALUES(1, 5, 441, CAST('20110202' AS DATETIME))
INSERT INTO #T VALUES(1, 15, 241, GETDATE())
INSERT INTO #T VALUES(1, 12, 241, GETDATE())
INSERT INTO #T VALUES(2, 12, 241, GETDATE())
SELECT * FROM #T
DECLARE #writer_id int = 1
My results:
Result Set (3 items)
points | project_id | created_date
20 | 441 | 04/02/2011 00:00:00
10 | 600 | 04/02/2011 00:00:00
15 | 241 | 21/09/2011 18:59:31

Answer 4

My solution use CROSS APPLY sub-queries.
For optimal performance I have created an index on project_id (ASC) & points (DESC sorting order) fields.
If you want to see all creation_date values that have maximum points then you can use WITH TIES:
CREATE TABLE dbo.Project
(
project_id INT PRIMARY KEY
,name NVARCHAR(100) NOT NULL
);
CREATE TABLE dbo.ProjectActivity
(
project_activity INT IDENTITY(1,1) PRIMARY KEY
,project_id INT NOT NULL REFERENCES dbo.Project(project_id)
,points INT NOT NULL
,creation_date DATE NOT NULL
);
CREATE INDEX IX_ProjectActivity_project_id_points_creation_date
ON dbo.ProjectActivity(project_id ASC, points DESC)
INCLUDE (creation_date);
GO
INSERT dbo.Project
VALUES (1, 'A'), (2, 'BB'), (3, 'CCC');
INSERT dbo.ProjectActivity (project_id, points, creation_date)
VALUES (1,100,'2011-01-01'), (1,110,'2011-02-02'), (1, 111, '2011-03-03'), (1, 111, '2011-04-04')
,(2, 20, '2011-02-02'), (2, 22, '2011-03-03')
,(3, 2, '2011-03-03');
SELECT p.*, ca.*
FROM dbo.Project p
CROSS APPLY
(
SELECT TOP(1) WITH TIES
pa.points, pa.creation_date
FROM dbo.ProjectActivity pa
WHERE pa.project_id = p.project_id
ORDER BY pa.points DESC
) ca;
DROP TABLE dbo.ProjectActivity;
DROP TABLE dbo.Project;