选择每个月的列总和

Question

i'm trying to get a sum of a column for each month. this is what i've done.

My SQL Query :

SELECT `ID_Pilot` ,`PilotStationDate`  ,`PilotWaitingTime`, ( SELECT FORMAT(SUM( `PilotWaitingTime` ),2) FROM pilot ) AS Total
FROM pilot

this is the result :

  ID_Pilot  PilotStationDate    PilotWaitingTime    Total
  P001      2013-01-01                       0.2    39.20
  P002      2013-01-02                      19.2    39.20
  P003      2013-01-03                       7.8    39.20
  P004      2013-02-04                       6.4    39.20
  P005      2013-02-06                       5.6    39.20

and this is the result i want :

ID_Pilot    PilotStationDate    PilotWaitingTime    Total
  P001      2013-01-01                       0.2    27.20
  P002      2013-01-02                      19.2    27.20
  P003      2013-01-03                       7.8    27.20
  P004      2013-02-04                       6.4    12.00
  P005      2013-02-06                       5.6    12.00

note: 27.20 in Total column is a sum of PilotWaitingTime in January and 12.00 is a sum of PilotWaitingTime in February

Thank you for your help

Answer 1

This query will return the sum for each month:

SELECT
  DATE_FORMAT(PilotStationDate, '%Y-%m') as year_month,
  FORMAT(SUM( `PilotWaitingTime` ),2) as total
FROM pilot
GROUP BY
  DATE_FORMAT(PilotStationDate, '%Y-%m')

then you just can join back this query with the pilot table:

SELECT
  p.`ID_Pilot`,
  p.`PilotStationDate`,
  p.`PilotWaitingTime`,
  t.total
FROM
  pilot p INNER JOIN (
    SELECT
      DATE_FORMAT(PilotStationDate, '%Y-%m') as year_month,
      FORMAT(SUM( `PilotWaitingTime` ),2) as total
    FROM pilot
    GROUP BY
      DATE_FORMAT(PilotStationDate, '%Y-%m')
  ) t ON DATE_FORMAT(p.PilotStationDate, '%Y-%m') = t.year_month

Answer 2

Your pilot table data would be helpful to provide the perfect query. But you can try these two queries.

SELECT `ID_Pilot` ,`PilotStationDate`  ,`PilotWaitingTime`, ( SELECT FORMAT(SUM( `PilotWaitingTime` ),2) FROM pilot p2 where p2.ID_Pilot = p1.ID_Pilot ) AS Total
FROM pilot p1;

OR

SELECT `ID_Pilot` ,`PilotStationDate`  ,`PilotWaitingTime`, FORMAT(SUM( `PilotWaitingTime`),2)  AS Total
    FROM pilot GROUP BY ID_Pilot;

Answer 3

Here's the query you could try out (Example http://sqlfiddle.com/#!9/96667/1 )

select pilot.*, totals.tot
from pilot
inner join
(
  select 
    year(pilotstationdate) as yr,
    month(pilotstationdate) as mth,
    sum(pilotwaitingtime) as tot
  from pilot
  group by 
    year(pilotstationdate),
    month(pilotstationdate)
) totals
  on year(pilot.pilotstationdate) = totals.yr
  and month(pilot.pilotstationdate) = totals.mth

Answer 4

select p.id_pilot, p.pilotstationdate, p.pilotwaitingtime,
(select sum(pilotwaitingtime) 
  from pilot 
  where last_day(pilotstationdate)=last_day(p.pilotstationdate)) total
from pilot p

last_day() is a mysql function that returns the last day of the month.