Want to learn how to compute the value for a Generated Column in PostgreSQL 15.

Here is the source code for this video:

select version()
show server_version;

drop table HR_Employee
create table HR_Employee
(
emp_id int not null,
annual_salary numeric not null,

--a generated column is a table column
--that is "always generated" from some other column or columns
--the computation must produce the same datatype
hourly_rate numeric generated always as (annual_salary / 2080) stored
)

insert into HR_Employee(emp_id, annual_salary)
values
(1, 35000.00),
(2, 50000.00),
(3, 100000.00);

select *
from HR_Employee

select *
from HR_Employee
where hourly_rate > 20

update HR_Employee
set annual_salary = 55000
where emp_id = 2;

what if i wanted to compute the value based on other values in other columns

lets say that i have 2 entities test and semester
and the entity test has a foreign key semester_id and a regular column credit_score

and the entity semester also has credit_score which is the sum of all the credit_score of all the tests that are related to the semester.
how would i compute the credit_score for semester.