>I have create a Employee Salary.dbf with six fields namely 1. Basic pay 2. Special Pay 3. Dearnes pay 4. House rent allowance 5. Transport allowance 6. Gross pay .
>
>For every year July The "Basic pay" (Field) will automatically increased by 3% for every Epmloyees.
>
>Let assume the "Basic pay" of a employee now is =7500, next year july it will automatically increased by 3%. The formula is 7500*0.03 = 225. so the basic pay of employee for next year july is 7500+225 = 7725.
>
>How to write source code?

This is the same as multiplying by 1.03: the 100% of the original salary plus the 3% increase makes a total of 103% of the original salary.

use SalaryTable
replace all base_salary with base_salary * 1.03
use

Be careful that you don't replace twice in the same year.

Also, you may want to review the structure of your table, so that you have base pay stored for different years (dividing by 1.03 is less accurate). This would require a secondary table, with one record for each employee and year. In this case, you would not only have to replace, but also create the new salary records. Lookup up the information would be more complicated, too; but the first priority should be to have sensible data structures, that allow the information to be consistent, complete, flexible, etc.

Oh, and also, you may want to replace only active employees. If you have a logical field IsActive:

replace all base_salary with base_salary * 1.03 for IsActive