postgres select non existing field as empty string-CodePudding

This might be a stupid question. Imaging following table in Postgres:

create table scientist (id integer, firstname varchar(100), lastname varchar(100));
insert into scientist (id, firstname, lastname) values (1, 'albert', 'einstein');

A simple select of all fields:

select  id, firstname, lastname   scientist;

results in:

is	firstname	lastname
1	albert	einstein

Is there some way to add a kind of non-existing empty virtual field f.e. age? Pseudo Code:

 select 
    id, 
    firstname, 
    lastname,
    age as '' -- my non existing field that should show up in the results
    from 
    scientist;

that the result looks like?

is	firstname	lastname	age
1	albert	einstein

CodePudding user response：

It's the other way round: as defines a column alias, so

'' as age

will work.

However, I'd be quite surprised about a column named age in a result that is a character value, not an integer. If you want a typed value, you can also use null::int as age