Question

In Excel we can create reference cell (e.g. A2 = A1 + 1). Or we create a reference cell on other sheet.

On postgres I would like create a reference cell to another table. Is it possible? How could I achieve that?

Thanks in advance

Answer 1

RDBMS uses a different approach. There are queries and data. When you query something, it is natural to perform extra calculations on the data. In your case this is a simple arythmetic function.

Say, you have a table:

CREATE TABLE tab (
  id  integer PRIMARY KEY,
  a1  integer
);

Now, to achieve your case you can do the following:

SELECT id,
       a1,
       a1+1 AS a2
  FROM tab;

As you can see, I’m using existing columns in the formula and assign the result a new alias a2.

I really recommend you to read the Tutorial and SQL Basics from the official PostgreSQL documentation, along with some SQL introduction book.