Error: ORA-01789: query block has incorrect number of result columns

Question

I have two relational views.

First view:

CREATE VIEW VIEW1
AS
SELECT T#,
MAX(DECODE(LEG#,1,DEPARTURE)) ORIGIN,
MAX(DECODE(LEG#,1,DESTINATION)) DESTINATION1
FROM TRIPLEG
WHERE T# IN
(SELECT T# FROM TRIPLEG WHERE LEG# < 3
AND T# IN
(SELECT T# FROM TRIPLEG GROUP BY T#
HAVING COUNT(T#) < 3)
GROUP BY T#)
GROUP BY T#
ORDER BY T#;

Second view:

CREATE VIEW VIEW2
AS
SELECT T#,
MAX(DECODE(LEG#,2,DESTINATION)) DESTINATION1
FROM TRIPLEG
WHERE T# IN
(SELECT T# FROM TRIPLEG WHERE LEG# < 3
AND T# IN
(SELECT T# FROM TRIPLEG GROUP BY T#
HAVING COUNT(T#) < 3)
GROUP BY T#)
GROUP BY T#
ORDER BY T#;

I use SELECT * FROM VIEW1 UNION ALL SELECT * FROM VIEW2

And I got the error ORA-01789.

What I want to achieve is

T#    |       ORIGIN   | DESTINATION1 | DESTINATION2
------------------------------------------------------
1            abc            efg           hij

is what I create considered relational views?

Answer 1

Both views must have the same number of columns in order to perform a UNION ALL. Look at Oracle reference: The UNION ALL, INTERSECT, MINUS Operators