Question

I have two tables:

Table1
id | col1 | col2 | other_id
---------------------------
1  | val1 | val2 | 2
2  | val3 | val4 | 3

Table2
id | col3 | other_id
--------------------
1  | val5 | 4

And I want to join this two tables in this way:

id | col1 | col2 | col3 | other_id
-----------------------------------
1  | val1 | val2 | NULL | 2
2  | val3 | val4 | NULL | 3
1  | NULL | NULL | val5 | 4

I create this SQL query:

(
SELECT * FROM table1 AS M LEFT JOIN table2 AS D ON M.other_id = D.other_id
)
UNION
(
SELECT * FROM table1 AS M RIGHT JOIN table2 AS D ON M.other_id = D.other_id
)

Result:

id   | col1 | col2 | other_id | id   | col3 | other_id
------------------------------------------------------
1    | val1 | val2 | 2        | NULL | NULL | NULL
2    | val3 | val4 | 3        | NULL | NULL | NULL
NULL | NULL | NULL | NULL     | 1    | val5 | 4

But I get multiple columns with same labels. I don’t want to use aliases, just join columns with the same name.

Answer 1

You can use UNION ALL for this and just put placeholders for the columns that do not exist in both tables:

select t1.id, t1.col1, t1.col2, null col3, t1.other_id
from table1 t1
union all
select t2.id, null col1, null col2, t2.col3, t2.other_id
from table2 t2

See SQL Fiddle with Demo

Result:

| ID |   COL1 |   COL2 |   COL3 | OTHER_ID |
--------------------------------------------
|  1 |   val1 |   val2 | (null) |        2 |
|  2 |   val3 |   val4 | (null) |        3 |
|  1 | (null) | (null) |   val5 |        4 |