Question about multiplying columns in SQL

Question

I was wondering if it was possible to multiply two columns and if so how would this take place

Suppose I have a table

a    b
1    4
2    5
3    6

Could I do something like

SELECT a *b from table

Would this multiply the contents row by row then store it in a new column

Are these result right

4
10
18

Answer 1

That query would multiply the values, but it wouldn't "store it in a new column" To store it you would have to issue an update statement.

Assuming you add a new column ("c") to your table you could do:

update table 
  set c = a * b

If all you need is the new column in a result set, without modifying the underlying table you could:

select a, b, (a*b) as c from table

Answer 2

Yes you can perfectly do that.

update

To clarify: The query and output you mentioned in your question are correct.

Answer 3

Rather than storing a calculated column in a base table, consider a viewed table:

CREATE VIEW MyView
AS
SELECT a, b, 
       a * b AS my_calc
  FROM MyTable;