Oracle Database Discussions

I wish to switch between several sets of identical tables under different schemas/owners in the same database - say dev1, dev2, test, prod schemas.

The (single) user I connect with (say - called Reader1) has granted select to all these tables, and now i wish to do something like:

alter session set schema='dev1'
;
select count(*) from customers
;
select count(*) from sales
;
alter session set schema='test'
;
select count(*) from customers
;
select count(*) from sales
;

The database should then translate it to something like:

select count(*) from dev1.customers
;
select count(*) from dev1.sales
;
select count(*) from prod.customers
;
select count(*) from prod.sales
;

Is this possible or does anyone have alternative suggestions ?