select isnull(isnull(a.key_id,b.key_id),c.key_id) key_id,
a.qty,b.qty,c.qty
from table_1 a full join table_2 b on a.key_id=b.key_id
full join table_3 c on a.key_id=c.key_id
a.qty,b.qty,c.qty
from table_1 a full join table_2 b on a.key_id=b.key_id
full join table_3 c on a.key_id=c.key_id
table_1=a.qty,
table_2=b.qty,
table_3=c.qty
from table1 a full join table2 b on a.key_id=b.key_Id
full join table3 c on a.key_id=c.key_id
select key_id,table_1=sum(table_1),table_2=sum(table_2),table_3=sum(table_3)
from(
select key_id,table_1=qty,table_2=0,table_3=0 from table_1
union all
select key_id,table_1=0,table_2=qty,table_3=0 from table_2
union all
select key_id,table_1=0,table_2=0,table_3=qty from table_3
)a group by key_id
,table_1=isnull(a.qty,'')
,table_2=isnull(b.qty,'')
,table_3=isnull(c.qty,'')
from table_1 a full join table_2 b on a.key_id=b.key_id
full join table_3 c on a.key_id=c.key_id
b.qty as table_1,
c.qty as table_2,
d.qty as table_3
from ( select key_id from table1
union
select key_id from table2
union
select key_id from table3
) a left join table1 b on a.key_id=b.key_id
left join table2 c on a.key_id=c.key_id
left join table3 d on a.key_id=d.key_id