SQL – Generate column from sum of columns from different table

I have two tables: The first one contains numeral values, it looks like this:

The id column is the primary key; it has the attribute AUTO_INCREMENT. All columns have the datatype INT.

Now my question: Can I create a table like the following:

create table testsumtable
(
    id int primary key auto_increment,
    sumColumn int generated always as (sum(SELECT intone, inttwo, intthree FROM valuestable WHERE id=new.id))
);

Answer

Are you just looking to create a generated column that contains the sum of the three other columns?

If so, you should add it directly to the original table:

alter table mytable
add column sumColumn as (intone + inttwo + intthree)

If you don’t want (or can’t) alter the original table, I would suggest creating a view instead:

create view myview as
select id, intone, inttwo, intthree, intone + inttwo + intthree sumColumn from mytable