Getting data for a user in a month - sql

Question

(The database is Postgres )
Let's say I have a table races with columns (user_name , race_time , race_speed , race_no).
Each users can have multiple races . I want to get data for each month and show for each month how many races are played in that month. But I also want to show which user played the most and which played has the maximum speed.
select
extract ( month from race_time) as month,
extract ( year from race_time) as year,
count(race_no) as total_races
from races r
group by year,month
order by year desc,month desc
The above query gives me each month and the total races but how can I find for each month which user played the most (that'd be one user)?
I hope someone could help me with this.

Answer 1

SQL Fiddle
with r as (
select
to_char(race_time, 'YYYY-MM') as month,
user_name,
count(*) as n_races,
max(race_speed) as max_speed
from races
group by 1, 2
), total_races as (
select sum(n_races) as total_races, month
from r
group by month
)
select *
from (
select distinct on (month)
month, user_name as user_most_races, n_races as most_races
from r
order by 1, 3 desc
) s
inner join (
select distinct on (month)
month, user_name as user_max_speed, max_speed
from r
order by 1, 3 desc
) q using (month)
inner join
total_races using(month)
order by month

Answer 2

SELECT COUNT(DISTINCT user_name), user_name, EXTRACT(month FROM race_time) AS month, EXTRACT(year FROM race_time) AS year
FROM races r
GROUP BY user_name, year, month
ORDER BY year desc, month desc

Answer 3

Try it!
USE [DATABASE_NAME]
GO
--this is calculating the which user played the most
CREATE FUNCTION [dbo].[GetHighestPlayedRaceUserByYearMonth]
(
-- Add the parameters for the function here
#Year INT, #Month INT
)
RETURNS NVARCHAR(50)
AS
BEGIN
-- Declare the return variable here
DECLARE #UserName NVARCHAR(50)
-- Add the T-SQL statements to compute the return value here
DECLARE #TempTbl TABLE(Played INT,UserName NVARCHAR(50))
INSERT INTO #TempTbl(Played,UserName)
SELECT
COUNT(race_no) AS Played,
[user_name] AS UserName
FROM Table_1
WHERE
YEAR(race_time)=#Year and
MONTH(race_time)=#Month
GROUP BY
MONTH(race_time),
YEAR(race_time),
[user_name]
ORDER BY
YEAR(race_time) DESC,
MONTH(race_time) DESC,
COUNT(race_no) DESC
DECLARE #MaxPlayed INT
SET #MaxPlayed=(SELECT TOP 1 Played FROM #TempTbl ORDER BY Played DESC)
DECLARE #TempTbl2 TABLE(ID INT IDENTITY(1,1) NOT NULL,UserName NVARCHAR(50))
INSERT INTO #TempTbl2
SELECT UserName FROM #TempTbl WHERE Played=#MaxPlayed
DECLARE #ROWCOUNT INT
SET #ROWCOUNT=1
SET #UserName=''
WHILE (SELECT COUNT(*) FROM #TempTbl2)>=#ROWCOUNT
BEGIN
IF (SELECT COUNT(*) FROM #TempTbl2)=#ROWCOUNT
BEGIN
SET #UserName= #UserName+(SELECT UserName FROM #TempTbl2 WHERE ID=#ROWCOUNT)
END
ELSE
BEGIN
SET #UserName= #UserName+(SELECT UserName FROM #TempTbl2 WHERE ID=#ROWCOUNT)+','
END
SET #ROWCOUNT=#ROWCOUNT+1
END
-- Return the result of the function
RETURN #UserName
END
GO
--this is calculating which user played with the maximum speed
CREATE FUNCTION [dbo].[GetMaxRaceSpeedUserByYearMonth]
(
-- Add the parameters for the function here
#Year INT, #Month INT
)
RETURNS NVARCHAR(50)
AS
BEGIN
-- Declare the return variable here
DECLARE #UserName NVARCHAR(50)
-- Add the T-SQL statements to compute the return value here
DECLARE #TempTbl TABLE(MaxRaceSpeed INT,UserName NVARCHAR(50))
INSERT INTO #TempTbl(MaxRaceSpeed,UserName)
SELECT
MAX(race_speed) AS MaxRaceSpeed,
[user_name] AS UserName
FROM Table_1
WHERE
YEAR(race_time)=#Year and
MONTH(race_time)=#Month
GROUP BY
MONTH(race_time),
YEAR(race_time),
[user_name]
ORDER BY
YEAR(race_time) DESC,
MONTH(race_time) DESC,
COUNT(race_no) DESC
DECLARE #MaxRaceSpeed INT
SET #MaxRaceSpeed=(SELECT TOP 1 MaxRaceSpeed FROM #TempTbl ORDER BY MaxRaceSpeed DESC)
DECLARE #TempTbl2 TABLE(ID INT IDENTITY(1,1) NOT NULL,UserName NVARCHAR(50))
INSERT INTO #TempTbl2
SELECT UserName FROM #TempTbl WHERE MaxRaceSpeed=#MaxRaceSpeed
DECLARE #ROWCOUNT INT
SET #ROWCOUNT=1
SET #UserName=''
WHILE (SELECT COUNT(*) FROM #TempTbl2)>=#ROWCOUNT
BEGIN
IF (SELECT COUNT(*) FROM #TempTbl2)=#ROWCOUNT
BEGIN
SET #UserName= #UserName+(SELECT UserName FROM #TempTbl2 WHERE ID=#ROWCOUNT)
END
ELSE
BEGIN
SET #UserName= #UserName+(SELECT UserName FROM #TempTbl2 WHERE ID=#ROWCOUNT)+','
END
SET #ROWCOUNT=#ROWCOUNT+1
END
-- Return the result of the function
RETURN #UserName
END
GO
--Select Query
SELECT
MONTH(race_time) AS [Month],
YEAR(race_time) AS [Year],
COUNT(race_no) AS RacePlayed,
dbo.GetHighestPlayedRaceUserByYearMonth(YEAR(race_time),MONTH(race_time)) AS MaximunPlayedUser,
dbo.GetMaxRaceSpeedUserByYearMonth(YEAR(race_time),MONTH(race_time)) AS MaximunSpeedUser
FROM TABLE_NAME
GROUP BY MONTH(race_time),YEAR(race_time)
ORDER BY YEAR(race_time) DESC,MONTH(race_time) DESC