How to subtact a Sum Amount from my table a from a value in my table b

Question

tableA :

tranactionid staffid amount 
1001          19052   2000
1002          19043   3000
1004          19076   4000

tableB :

BudgetCode Budget
271098     20000

I want to sum Amount in tableA and subtract it from Budget value 20000

20000 - 9000 = 11000

Answer 1

您必须使用：

 SELECT (SELECT [Budget] FROM tableB) - (SELECT SUM([amount]) FROM tableA) AS [any_name]

Answer 2

This will work if TableB has just one row forever, but it's likely your requirements go beyond that:

SELECT tableB.Budget - (SELECT SUM(amount) FROM tableA)
FROM tableB.Budget;