Query to apply rate from the interval of dates - sql

Question

Let's say I have two tables in my oracle database
Table A : stDate, endDate, salary
For example:
03/02/2010 28/02/2010 2000
05/03/2012 29/03/2012 2500
Table B : DateOfActivation, rate
For example:
01/01/2010 1.023
01/11/2011 1.063
01/01/2012 1.075
I would like to have a SQL query displaying the sum of salary of table A with each salary multiplied by the rate of table B depending on the activation date.
Here, for the first salary the good rate is the first one (1.023) because the second rate has a date of activation that is later than stDate and endDate interval.
For the second salary, the third rate is applied because activation date of the rate was before the interval of dates of the second salary.
so the sum is this one : 2000 * 1.023 + 2500 * 1.075 = 4733.5
I hope I am clear
Thanks

Answer 1

Assuming the rate must be active before the beginning of the interval (i.e. DateOfActivation < stDate), you could do something like this (see fiddle):
SELECT SUM(salary*
(SELECT rate from TableB WHERE DateOfActivation=
(SELECT MAX(DateOfActivation) FROM TableB WHERE DateOfActivation < stDate)
)) FROM TableA;

Answer 2

This problem becomes much easier if DateofActivation is a true effective dated table with rate_start_date and rate_end_date such that a new row cannot be created where its start date or end_date will lie within an existing rate_start_date -- rate_end_date pair. The currently active row typically would have a NULL value for rate_end_date. In addition, Likely, you would want an EMP_ID on the salary table to be able to sum the rows to finish the calculation; and one needs to consider the following cases:
Start Date is between rate_start and rate_end
End Date is between rate_start and rate_end
Rate_start and Rate_end are between start_date and end_date (sandwiched)
If you run the following snippet you will see we can artificially create our rate_end_dates as follows:
SELECT D.ACTIVEDATE, D.RATE, NVL(MIN(E.ACTIVEDATE)-1,SYSDATE) ENDDATE
FROM XX_DATEOFACTIVATION D, XX_DATEOFACTIVATION E
WHERE D.ACTIVEDATE<E.ACTIVEDATE(+)
GROUP BY D.ACTIVEDATE, D.RATE
ORDER BY D.ACTIVEDATE
Proposed code is as follows:
SELECT DISTINCT * FROM
(SELECT S.*, T.RATE, S.SALARY*T.RATE
FROM XX_SAL_HIST S,
(SELECT D.ACTIVEDATE, D.RATE, NVL(MIN(E.ACTIVEDATE)-1,SYSDATE) ENDDATE
FROM XX_DATEOFACTIVATION D, XX_DATEOFACTIVATION E
WHERE D.ACTIVEDATE<E.ACTIVEDATE(+)
GROUP BY D.ACTIVEDATE, D.RATE) T -- creating synthetic rate_end_date
WHERE S.STDATE BETWEEN T.ACTIVEDATE AND T.ENDDATE)
UNION
(SELECT S.*, T.RATE, S.SALARY*T.RATE
FROM XX_SAL_HIST S,
(SELECT D.ACTIVEDATE, D.RATE, NVL(MIN(E.ACTIVEDATE)-1,SYSDATE) ENDDATE
FROM XX_DATEOFACTIVATION D, XX_DATEOFACTIVATION E
WHERE D.ACTIVEDATE<E.ACTIVEDATE(+)
GROUP BY D.ACTIVEDATE, D.RATE) T -- creating synthetic rate_end_date
WHERE S.ENDDATE BETWEEN T.ACTIVEDATE AND T.ENDDATE)
UNION
(SELECT S.*, T.RATE, S.SALARY*T.RATE
FROM XX_SAL_HIST S,
(SELECT D.ACTIVEDATE, D.RATE, NVL(MIN(E.ACTIVEDATE)-1,SYSDATE) ENDDATE
FROM XX_DATEOFACTIVATION D, XX_DATEOFACTIVATION E
WHERE D.ACTIVEDATE<E.ACTIVEDATE(+)
GROUP BY D.ACTIVEDATE, D.RATE) T -- creating synthetic rate_end_date
WHERE T.ACTIVEDATE BETWEEN S.STDATE AND S.ENDDATE)

Answer 3

The first thing to do is to transform Table B (Table2 in the query) to have, for each row, the start and end date
Select DateOfActivation AS startDate
, rate
, NVL(LEAD(DateOfActivation, 1) OVER (ORDER BY DateOfActivation)
, TO_DATE('9999/12/31', 'yyyy/mm/dd')) AS endDate
From Table2
Now we can join this table with Table A (Table1 in the query)
WITH Rates AS (
Select DateOfActivation AS startDate
, rate
, NVL(LEAD(DateOfActivation, 1) OVER (ORDER BY DateOfActivation)
, TO_DATE('9999/12/31', 'yyyy/mm/dd')) AS endDate
From Table2)
Select SUM(s.salary * r.rate)
From Rates r
INNER JOIN Table1 s ON s.stDate < r.endDate AND s.endDate > r.startDate
The JOIN condition get every row in Table A that are at least partially in the activation period of the rate, if you need it to be inclusive you can alter it as in the following query
WITH Rates AS (
Select DateOfActivation AS startDate
, rate
, NVL(LEAD(DateOfActivation, 1) OVER (ORDER BY DateOfActivation)
, TO_DATE('9999/12/31', 'yyyy/mm/dd')) AS endDate
From Table2)
Select SUM(s.salary * r.rate)
From Rates r
INNER JOIN Table1 s ON s.stDate >= r.startDate AND s.endDate <= r.endDate