在sql中加入计算

Question

I am trying to achieve staggered calculation in joins in sql 2008. I can have n number of rows for 1 job id. I have created a sample below

CREATE TABLE Job
(
  JobID INT NOT NULL,
  Amount INT NOT NULL
);

INSERT INTO Job (JobID, Amount)
    VALUES (1, 25),
        (1, 45),
        (1, 40),
        (2, 25),
        (3, 26),
        (3, 26);

now the discount for JobID = 1 is 80 , So what I am expecting in output of query result is below:

If the Amount > Discount , so show the finalvalue = Amount - Discount but if Amount < Discount , then show Finalvalue = Amount - Amount , and if Discount is still left , deduct the same from the subsequent rows.

Job ID  Amount  FinalValue
1        25       0
1        45       0
1        40      30

Can all this be done in a join?

Answer 1

Here you are:

EDIT: ATTENTION: You should add a column for sorting. My approach is partitioning AND sorting by JobID which makes the output random...

EDIT: Sorry, did not add the tables...

CREATE TABLE Job
(
    JobID INT NOT NULL,
    Amount INT NOT NULL
);

INSERT INTO Job (JobID, Amount)
    VALUES (1, 25), (1, 45), (1, 40), (2, 25), (3, 26), (3, 26);

CREATE TABLE Discount
(
    JobID INT NOT NULL,
    Discount INT NOT NULL
);
INSERT INTO Discount(JobID,Discount)VALUES(1,80),(2,0),(3,10);
    WITH myCTE AS
    (
        SELECT ROW_NUMBER() OVER(PARTITION BY Job.JobID ORDER BY Job.JobID) AS inx
              ,Job.JobID
              ,Job.Amount
              ,Discount.Discount     
        FROM Job
        INNER JOIN Discount ON Job.JobID=Discount.JobID
    )
    SELECT * FROM myCTE
    CROSS APPLY
    (
        SELECT SUM(x.Amount)
        FROM myCTE AS x
        WHERE x.JobID=myCTE.JobID
          AND x.inx<=myCTE.inx  
    ) AS AmountCummulativ(AmountCummulativ)
    CROSS APPLY(SELECT AmountCummulativ-myCTE.Discount) AS DiscountCalculated(DiscountCalculated)
    CROSS APPLY(SELECT CASE WHEN DiscountCalculated<0 THEN 0 ELSE DiscountCalculated END) AS DiscountResolved(DiscountResolved)

Hope this helps

Answer 2

I think what you are looking for can be done using a case statement

select a.jobid,a.Amount,case when a.amount > b.discount then a.amount - b.discount else 0 end final_value

from Job a inner join Job_discount b on a.jobid = b.jobid

You can look at the results here http://sqlfiddle.com/#!3/f9a46/1

I had to assume the discount table structure

Answer 3

I added some sequence (row number) for the Job table (calling it JobOrder), to increment the sums. You can change the order as it is now for JobId, Amount!

With JobOrder as (
  -- Job order by id and amount
  select row_number() over (order by JobID, Amount asc) as rowno, JobId, Amount from Job
),
JobSumIncr as (
  select 
  JobID, 
  Amount, 
  (select sum(Amount)
   from JobOrder j2
   where j2.JobID = j.JobID and j2.RowNo <= j.RowNo
  ) as AmountTotal
  from JobOrder j
)
select 
  j.JobID,
  j.Amount,
  j.AmountTotal,
  d.Discount,
  (case when d.Discount>=j.AmountTotal then 0 else j.AmountTotal-d.Discount end) as FinalValue
from
  JobSumIncr j left join Discount d on j.JobID = d.JobID; 

Asuming that your Discount table is something like:

CREATE TABLE Discount (
    JobID INT,
    Discount INT 
);

SqlFiddle here! and for a more secure Sql (checking null values and see the discount left) see this SQLFiddle too .

A version which keeps track of the discount left, see sqlfiddle-2 above.

Answer 4

You can try following code : 80 is the discount amount

Select JobID,  Amount,
case when SUM (Amount) OVER (partition by JobID ORDER BY JobID ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) > 80 then SUM(Amount) OVER (partition by JobID ORDER BY JobID ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) - 80 else 0 end as FinalValue
from Job