Use temporary tables to store the results and check if they return something before selecting from them

SELECT 1 Test INTO #t1

SELECT 2 Test INTO #t2

DELETE #t2 --now #t2 is empty

SELECT 3 Test INTO #t3

IF EXISTS(SELECT 1 FROM #t1)

SELECT * FROM #t1

IF EXISTS(SELECT 1 FROM #t2)

SELECT * FROM #t2

IF EXISTS(SELECT 1 FROM #t3)

SELECT * FROM #t3