Note - Read about the JOIN operator here

Question-

File A has:

a11, a12
a21, a22

File B has:

a11, b12
b21, b22

Question

If we run the below commands

A = load 'A' as (f, s);
B = load 'B' as (f, t);
E = join A by f RIGHT, B by f;
dump E;

then the output will be

(a11,a12,a11,b12)
(,,b21,b22)