Question

I have two tables

Master  
Detail

In the Master & Detail table, i have an Amount field

I need to get the SUM of Amount in Detail and subtract it from Amount in Master and display in “Current_Amount”

“Current_Amount” should equal to “Master.Amount” – Sum of “Detail.Amount”

Answer 1

Without having a ton of details on the two tables, this will give you the total:

SELECT (Max(M.Amount) - SUM(D.Amount)) as CurrentAmount
FROM Master M
INNER JOIN Detail D
    ON M.ID = D.ID

Then if you want the Master Id included:

SELECT M.ID, (Max(M.Amount) - SUM(D.Amount)) as CurrentAmount
FROM Master M
INNER JOIN Detail D
    ON M.ID = D.ID
GROUP BY M.ID