SQL Server 2012

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CREATE TABLE tab(ColumnA DECIMAL(10,2), ColumnB DECIMAL(10,2), ColumnC DECIMAL(10,2))
INSERT INTO tab(ColumnA, ColumnB, ColumnC) VALUES (2, 10, 2),(3, 15, 6),(7, 14, 3)
3 rows affected

SELECT *
FROM tab


ColumnA
ColumnB
ColumnC


2.00
10.00
2.00

3.00
15.00
6.00

7.00
14.00
3.00


SELECT
  ColumnA,
  ColumnB,
  sub.calccolumn1,
  sub.calccolumn1 / ColumnC AS calccolumn2
FROM tab t
CROSS APPLY (VALUES (t.ColumnA + t.ColumnB)) AS sub(calccolumn1);


ColumnA
ColumnB
calccolumn1
calccolumn2


2.00
10.00
12.00
6.0000000000000

3.00
15.00
18.00
3.0000000000000

7.00
14.00
21.00
7.0000000000000


SELECT
  ColumnA,
  ColumnB,
  sub.calccolumn1,
  sub.calccolumn1 / ColumnC AS calccolumn2
FROM tab t
CROSS APPLY (VALUES (t.ColumnA + t.ColumnB)) AS sub(calccolumn1)
WHERE sub.calccolumn1 =  12; 


ColumnA
ColumnB
calccolumn1
calccolumn2


2.00
10.00
12.00
6.0000000000000

ColumnA	ColumnB	calccolumn1	calccolumn2
2.00	10.00	12.00	6.0000000000000
3.00	15.00	18.00	3.0000000000000
7.00	14.00	21.00	7.0000000000000