how to add computed columns in sql??

I also tried in that way but while filling the formula for computed column specifications property of deduction column like ([dbo].[deduction]([pf],[it] ,[medicalallwnceded] )) i m getting error as
"Computed column 'pf' in table 'Tmp_ps' is not allowed to be used in another computed-column definition." as i m using pf : 0.25*salary.
So,i tried to put the formula for deduction as:
(((0.25)*[salary])+[it]+[medicalallwnceded]) which is working but its getting more complex..plz suggest.

Hi Priya,

I've created a sample Table, Function and tested it. Works like a charm. Check the script below:
------------------------------------------------------------------------
CREATE TABLE TEST(
SALARY FLOAT,
PF AS (SALARY*.025),
IT FLOAT,
MEDICAL FLOAT

)
---------------------------------------------------------------------
CREATE FUNCTION GetDeduction(@pf FLOAT, @it FLOAT, @medical FLOAT)
RETURNS FLOAT
AS
BEGIN
DECLARE @deduction FLOAT;
SET @deduction=@pf+@it+@medical;
RETURN @deduction;
END
--------------------------------------------------------------------------
INSERT INTO TEST(SALARY, IT, MEDICAL) VALUES(20000,200,300);
SELECT * FROM TEST;
SELECT *, dbo.GetDeduction(PF, IT, MEDICAL)AS DEDUCTION FROM TEST;

--------------------------------------------------------------------------

Give it a go and let me know if it works.

mark this as answer if it helps!
Thanks.