Computed columns in SQL are calculated columns where the value of the column will be automatically inserted according to the formula specified.
Suppose Net salary = Gross_salary – PF, so this can be created as,
Create table Employee(empno, empname, Basic, HRA, PF, Gross_Sal = Basic+HRA,Net_salary = Gross_salary-PF)
When you query Select * from Employee, all the fields along with the calculated column values will get displayed. Even if you update on the field, changes will be automatically done in calculated column.