SQL 从另一个表的余额中减去一个表中的值超过多行

Question

I have a job that runs once per day against two tables, one containing an employees current holiday and PTO balances (dbo.Balance) and another containing new absences (dbo.Absence). All values are in minutes.

I'm trying to use logic to determine how much time each absence (previous day) should be applied to holiday, pto, or unpaid. It should apply in the following order: 1) Holiday, 2) PTO, 3) Unpaid. I was fine with the below code until an employee took two separate absences on the same day. I've been beating my head on this for a week and can't figure out how to get it to basically have a running balance for each bucket at run time.

The actual job is more complex and involves modifying start and end times for each record based on this output - so I do need a separate line for each absence record.

dbo.Balance

| EmpId | HolidayBal | PTOBal |
|:------|:----------:|-------:|
|   1   |     60     |  120   |
|   2   |    240     |  600   |
|   3   |      0     |    0   |

dbo.Absence

| EmpId | Time Taken | 
|:------|-----------:|
|   1   |    210     |
|   1   |     45     |
|   2   |    120     |
|   3   |    120     |

What I would like the result to look like:

| EmpId | TimeTaken  | HolidayUsed | PTOUsed | Unpaid |
|:------|:----------:|:-----------:|:-------:|:------:|
|   1   |    210     |      60     |   120   |   30   |
|   1   |     45     |       0     |     0   |   45   |
|   2   |    120     |     120     |     0   |    0   |
|   3   |    120     |       0     |     0   |  120   |

This is the code I have so far, just doesn't apply correctly when there is more than 1 absence in a day.

SELECT 
        BAL.EmpId
        ,BAL.HolidayBalance
        ,BAL.PTOBalance
        ,AB.TimeTaken

        ,CASE --HOLIDAY CALCULATION
            WHEN BAL.HolidayBalance - AB.TimeTaken >= 0 THEN -- HOLIDAY BALANCE EXCEEDS TIME USED, ALL TIME USED AS HOLIDAY
                AB.TimeTaken
            WHEN BAL.HolidayBalance > 0 AND BAL.HolidayBalance - AB.TimeTaken < 0 THEN -- TIME USED EXCEEDS HOLIDAY BALANCE, ALL HOLIDAY BALANCE USED
                BAL.HolidayBalance
            ELSE 
                0
            END AS HolidayUsed
        ,CASE -- PTO CALCULATION
            WHEN BAL.HolidayBalance - AB.TimeTaken >= 0 THEN -- ALL TIME USED AS HOLIDAY
                0
            WHEN BAL.HolidayBalance > 0 AND BAL.HolidayBalance - AB.TimeTaken < 0 THEN -- HOLIDAY BALANCE WAS LESS THAN TIME USED, HAVE A REMAINDER
                CASE
                    WHEN ((BAL.PTOBalance) - (AB.TimeTaken - BAL.HolidayBalance)) >= 0 THEN -- HAVE ENOUGH PTO BALANCE TO COVER REMAINDER
                        ((BAL.PTOBalance) - (AB.TimeTaken - BAL.HolidayBalance))
                    WHEN  BAL.PTOBalance > 0 AND ((BAL.PTOBalance) - (AB.TimeTaken - BAL.HolidayBalance)) < 0 THEN -- HAVE A PTO BALANCE BUT DOES NOT COVER REMAINDER
                        BAL.PTOBalance
                    ELSE
                        0
                END
            WHEN BAL.PTOBalance > 0 AND BAL.HolidayBalance = 0 AND BAL.PTOBalance - AB.TimeTaken >=0 THEN -- HAVE PTO TO COVER IT AND NO HOLIDAY BALLANCE.
                AB.TimeTaken
            WHEN BAL.PTOBalance > 0 AND BAL.HolidayBalance = 0 AND AB.TimeTaken > BAL.PTOBalance THEN-- HAVE NO HOLIDAY AND PTO BALANCE DOES NOT COVER EVERYTHING
                BAL.PTOBalance
            ELSE 0
            END AS PTOUsed
            ,CASE -- UNPAID CALCULATION
                WHEN BAL.PTOBalance + BAL.HolidayBalance - AB.TimeTaken < 0 THEN --NOT ENOUGH PTO OR HOLIDAY TO COVER ABSENCE
                    AB.TimeTaken - (BAL.PTOBalance + BAL.HolidayBalance)
                ELSE    
                    0
            END AS Unpaid
FROM    dbo.Balance BAL
        INNER JOIN dbo.Absence AB ON BAL.EmpId = AB.EmpId

Answer 1

Thanks for y'alls input. I finally figured it out. Had to basically add a running sum of the absence value (AbsenceSum) and then some tricky calculations to get everything to balance correctly. Wanted to post my solution should someone else have something similar!

SELECT
    EmpId
    ,TimeTaken
    ,StartTime
    ,HolidayUsed
    ,PTOUsed
    ,CASE
        WHEN TimeTaken - (HolidayUsed + PTOUsed) > 0 THEN -- HAVE A BALANCE NEEDING UNPAID
            TimeTaken - (HolidayUsed + PTOUsed)
        ELSE
            0
    END AS Unpaid
FROM (
    SELECT 
        AB.EmpId
        ,TimeTaken
        ,AB.AbsenceSum
        ,StartTime
        ,CASE 
            WHEN BAL.HolidayBal > (AbsenceSum - TimeTaken) THEN -- HAVE HOL BALANCE AVAILABLE TO USE
                CASE 
                    WHEN TimeTaken >= BAL.HolidayBal - (AbsenceSum - TimeTaken) THEN -- NOT ENOUGH HOL TO COVER ENTIRE ABSENCE?
                        BAL.HolidayBal - (AbsenceSum - TimeTaken) -- NOT ENOUGH, USE WHAT'S LEFT
                    ELSE 
                        TimeTaken 
                    END -- ELSE USE ENTIRE ABSENCE AS HOL
            ELSE 
                0 
            END HolidayUsed -- NO AVAILABLE HOL
        ,CASE WHEN BAL.HolidayBal > (AbsenceSum - TimeTaken) THEN -- HAVE HOL BALANCE AVAILABLE TO USE
                (CASE 
                    WHEN TimeTaken >= BAL.HolidayBal - (AbsenceSum - TimeTaken) THEN -- HOL COVERED SOME BUT NOT ALL
                        CASE
                            WHEN BAL.PTOBal > 0 THEN --HAVE PTO AVAILABLE
                                CASE
                                    WHEN BAL.PTOBal >= TimeTaken - (BAL.HolidayBal - (AbsenceSum - TimeTaken)) THEN -- PTO COVERS ALL OF REMAINDER
                                        TimeTaken - (BAL.HolidayBal - (AbsenceSum - TimeTaken))
                                    ELSE --PTO ONLY COVERS SOME
                                        BAL.PTOBal
                                END
                            ELSE
                                0
                        END
                    ELSE --HOL COVERED ENTIRE ABSENCE
                        0
                END)                
            ELSE -- NO HOL TO USE, MOVE TO PTO
                CASE 
                    WHEN BAL.PTOBal - ((AbsenceSum - TimeTaken) - BAL.HolidayBal) > 0 THEN -- HAVE PTO TO USE?
                        CASE 
                            WHEN TimeTaken >= BAL.PTOBal - ((AbsenceSum - TimeTaken) - BAL.HolidayBal) THEN -- HAVE ENOUGH PTO TO COVER ENTIRE ABSENCE?
                                BAL.PTOBal - ((AbsenceSum - TimeTaken) - BAL.HolidayBal) -- NOT ENOUGH, USE WHAT IS LEFT
                            ELSE 
                                TimeTaken 
                        END
                    ELSE
                        0
                END
            END AS PTOUsed
    FROM (
        SELECT EmpId, TimeTaken, ScheduleID, StartTime,
        SUM(TimeTaken) OVER (PARTITION BY EmpId ORDER BY ScheduleID, StartTime) AbsenceSum
        FROM dbo.Absence
    )AB 
        INNER JOIN dbo.Balance BAL ON BAL.EmpId = AB.EmpId
    )A
ORDER BY EmpId

Answer 2

This won't give you separate lines for each case, but it will do the calculation correctly. It might be a great interim solution.

Create a CTE with the sum of all the time off for the day as follows:

WITH total_absense AS 
(
    SELECT DISTINCT EmpID, SUM([Time Taken]) OVER(PARTITION BY EmpID)
    FROM dbo.Absense
)

Then replace dbo.absense with total_absense in your script.