SQL - 2個月之間的薪酬差異（差異）

Question

有2個單獨的SQL查詢返回NetPay金額MonthWise。 I 想要合併它們意味着我想要2個月的差異 （第2個月金額 - 第1個月金額）作爲輸出。

Query - 1 
Select ISNULL(Sum(EPS.Amount),0) as Amount 
From Payslip EPS 
Where EPS.Emp_Id = 5 and EPS.Month_Id = 5 

Query - 2 
Select ISNULL(Sum(EPS.Amount),0) as Amount 
From Payslip EPS 
Where EPS.Emp_Id = 5 and EPS.Month_Id = 6 

Answer 1

您可以使用Conditional Aggregation到這兩個查詢

Select Sum(case EPS.Month_Id when 6 then EPS.Amount else -EPS.Amount end) as Variance 
From Payslip EPS 
Where EPS.Emp_Id = 5 and EPS.Month_Id in (6,5) 

或

Select Sum(case EPS.Month_Id when 6 then EPS.Amount else 0 end) - 
     Sum(case EPS.Month_Id when 5 then EPS.Amount else 0 end) 
From Payslip EPS 
Where EPS.Emp_Id = 5 and EPS.Month_Id in (6,5) 

結合可以在where條款和Case聲明更換個月，如果它是不固定的。

使用幾個月動態

SELECT Isnull(A.Amount, 0) - Isnull(B.amount, 0) 
FROM (SELECT months, 
       Amount = Sum(Amount) 
     FROM #payslips 
     GROUP BY months) a 
     INNER JOIN (SELECT months, 
         Amount = Sum(Amount) 
        FROM #payslips 
        GROUP BY months) b 
       ON a.months = b.months + 1 
WHERE a.months = 6 
     AND b.months = 5 

的另一種方法對於較新的版本中，我們可以使用LAG窗函數

Answer 2

如果你不想在同一個查詢中加入你的更好的可視性，使用UNION ALL

Select Amount1-Amount As Variance 
from 
(
Select ISNULL(Sum(EPS.Amount),0) as Amount, '0.00' Amount1 
From Payslip EPS 
Where EPS.Emp_Id = 5 and EPS.Month_Id = 5 

UNION ALL 

Select '0.00' Amount, ISNULL(Sum(EPS.Amount),0) as Amount1 
From Payslip EPS 
Where EPS.Emp_Id = 5 and EPS.Month_Id = 6 

)am 

Answer 3

DECLARE @month1 INT 
DECLARE @month2 INT 

SET @month1= 5 
SET @month2= 6 

Select (a.month1Amount-b.month2Amount) AS Variance from 
(Select ISNULL(Sum(EPS.Amount),0) as month1Amount,EPS.Emp_Id 
From Payslip EPS 
Where EPS.Emp_Id = 5 and EPS.Month_Id =@month1 GROUP BY EPS.Emp_Id)a 
INNER JOIN 
(Select ISNULL(Sum(EPS.Amount),0) as month2Amount, EPS.Emp_Id 
From Payslip EPS 
Where EPS.Emp_Id = 5 and EPS.Month_Id =@month2 GROUP BY EPS.Emp_Id)b 
on a.Emp_Id=b.Emp_Id 

您可以動態提供月份。希望這個作品