What is joins?where we use it. is it DD concept? abap

Question

hi abapers,
what is joins?where we use it. is it DD concept?
  regards,
  anjan

Answer 1

hi srinivas.
chk this simple example.
u will get good idea.
table emp
empno name
a sasi
b xxx
c yyy
table sal
empno salary
a 1000
b 2000
Inner join
select eempno ename
s~sal
into table int_table
from emp as e
inner join sal
on
eempno = sempno.
if you made inner join between table a and b by emp no
the selection retrives only if the condition satisfy the output will be
a sasi 1000
b xxx 2000
Outer join
select eempno ename
s~sal into table  int_table
from emp as e
LEFT OUTER JOIN sal
on
eempno = sempno.
if you made outer join (left /right ) the left table kept as it is the
if the condition satisfy the right table entries will fetch else leave it blank
the output will be
a sasi a 1000
b xxx b 2000
c yyy
rgds
anver
if helped mark points