SQL Subtract the values of two resultsets - sql

Question

Is there an operator eavailable similar to UNION that will allow one query's resultset to be subtracted from another?
eg:
Result of a UNION
2 3 2 6 1 2 6 3 7
1 3 5 2 7 8 4 3 2
Result of potential subtraction operator
1 0 -3 4 -6 -6 2 0 5

Answer 1

You case is much simpler: just subtract one column from another
CREATE TABLE #A
(
col1 INT NOT NULL
,col2 INT NOT NULL
);
INSERT INTO #A (col1,col2)
VALUES
(2,1)
,(3,3)
,(2,5)
,(6,2)
,(1,7)
,(2,8)
,(6,4)
,(3,3)
,(7,2)
SELECT (col1 - col2) AS result
FROM #A;
DROP TABLE #A;
Original answer
So if I understand you correctly you need to Subtract two one dimensional matrixes. Sql Server is not really the best tool to do such a math, but here is the example how you can achieve your goal. The idea is simple: introduce indexes (i,j) and join by them (you can skip j since you matrix is one-dimensional, the example works for two-dimensional arrays):
CREATE TABLE #A
(
element_value INT NOT NULL
,i INT NOT NULL
,j INT NOT NULL
,PRIMARY KEY (i, j)
);
CREATE TABLE #B
(
element_value INT NOT NULL
,i INT NOT NULL
,j INT NOT NULL
,PRIMARY KEY (i, j)
);
INSERT INTO #A (element_value,i,j)
VALUES
(2,1,1)
,(3,1,2)
,(2,1,3)
,(6,1,4)
,(1,1,5)
,(2,1,6)
,(6,1,7)
,(3,1,8)
,(7,1,9)
INSERT INTO #B (element_value,i,j)
VALUES
(1,1,1)
,(3,1,2)
,(5,1,3)
,(2,1,4)
,(7,1,5)
,(8,1,6)
,(4,1,7)
,(3,1,8)
,(2,1,9)
SELECT (A.element_value - B.element_value) AS result
FROM #A AS A,#B AS B
WHERE A.i = B.i
AND A.j = B.j;
DROP TABLE #A;
DROP TABLE #B;