Add a row at the end of SQL Select using UNION

Question

I created a view in a record using some filters and i have to add lines that contains just ids from another table and a specific row at the end of the sql result.

So the expected result is something like that:

    Column 1 | Column 2 | Column 3 | Column4
1   0001     | 565      | AM1      | DR01
.
.
59  TEST1    |          |          |
60  NON_IMMO |          |          |

Line 59 is the id from the second table and line 60 is the specifix row. My query is like that :

SELECT DISTINCT a.asset_id 
 , a.serial_id 
 , a.VIN 
 , b.project_id 
  FROM ps_asset a 
 WHERE --Some conditions  
  UNION 
 SELECT PO_GROUP_ID 
 ,' ' 
 , ' ' 
 , ' ' 
  FROM PS_PO_GROUP_TBL 
  UNION 
 SELECT 'NON_IMMO' 
 ,' ' 
 ,' ' 
 ,' ' 
  FROM dual

But the problem is using this I don't get the specific row at the end.

I feel like the SGBD show the 2 UNIONS ordered by alphabet.

    Column 1 | Column 2 | Column 3 | Column4
1   0001     | 565      | AM1      | DR01
.
.
59  NON_IMMO |          |          |
60  TEST1    |          |          |

Thanks for help.

Answer 1

Change the last UNION to a UNION ALL to skip elimination of duplicates (which as a side effect orders the lines). That should be enough...

...
FROM PS_PO_GROUP_TBL 
UNION ALL
SELECT 'NON_IMMO' 
...