--create a table for some sample data

IF OBJECT_ID('tempdb..#TempTable') IS NOT NULL
DROP TABLE #TempTable

CREATE TABLE #TempTable (
    [ID] INT NOT NULL,
    [Col1] INT NULL,
    [Col2] INT NULL,
    PRIMARY KEY (ID))
 
--insert random numbers with a few nulls tossed in

INSERT INTO #TempTable
SELECT 1,ABS(CAST(NEWID() AS BINARY(6))%10)+1,ABS(CAST(NEWID() AS BINARY(6))%10)+1
UNION
SELECT 2,ABS(CAST(NEWID() AS BINARY(6))%10)+1,ABS(CAST(NEWID() AS BINARY(6))%10)+1
UNION
SELECT 3,NULL,ABS(CAST(NEWID() AS BINARY(6))%10)+1
UNION
SELECT 4,ABS(CAST(NEWID() AS BINARY(6))%10)+1,ABS(CAST(NEWID() AS BINARY(6))%10)+1
UNION
SELECT 5,ABS(CAST(NEWID() AS BINARY(6))%10)+1,NULL
UNION
SELECT 6,ABS(CAST(NEWID() AS BINARY(6))%10)+1,ABS(CAST(NEWID() AS BINARY(6))%10)+1

--raw table

SELECT * FROM #TempTable ORDER BY ID

--Col1+Col2 = Col3

SELECT
     ID
    ,Col1
    ,Col2
    ,Col3 = ISNULL(Col1,0) + ISNULL(Col2,0)
FROM
    #TempTable
ORDER BY
    ID

almany_13 (1/27/2013)

---

SELECT name, (CASE WHEN(salary) <= 0 THEN NULL ELSE salary END) 
		   + (CASE WHEN(bonuses) <= 0 THEN NULL ELSE bonuses END) ) as total 
FROM YourTableName

 SELECT Name,
        Total = ISNULL(Salary,0) + ISNULL(Bonuses,0)
   FROM dbo.YourTable
;