Oracle 21c

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CREATE TABLE DT1 (Column0, Column1, column3, column42) AS
SELECT 1234,  'example', 345,  'final1' FROM DUAL UNION ALL
SELECT 1234,  'example', 567,  'final3' FROM DUAL UNION ALL
SELECT 1234,  'example', 789,  'final5' FROM DUAL UNION ALL
SELECT 12345, 'example', 7890, 'final9' FROM DUAL UNION ALL
SELECT 12345, 'example', 890,  'final10' FROM DUAL;
5 rows affected

CREATE TABLE DT2 (Column0, Column1, column3, column42) AS
SELECT 4567,  'example', 345,  'final1' FROM DUAL UNION ALL
SELECT 4567,  'example', 567,  'final3' FROM DUAL UNION ALL
SELECT 4567,  'example', 789,  'final5' FROM DUAL UNION ALL
SELECT 45678, 'example', 7890, 'final9' FROM DUAL UNION ALL
SELECT 45678, 'example', 890,  'final10' FROM DUAL;
5 rows affected

SELECT column0, column1, column3, column42
FROM   DT1
UNION ALL
SELECT column0, column1, column3, column42
FROM   DT2;


COLUMN0
COLUMN1
COLUMN3
COLUMN42


1234
example
345
final1

1234
example
567
final3

1234
example
789
final5

12345
example
7890
final9

12345
example
890
final10

4567
example
345
final1

4567
example
567
final3

4567
example
789
final5

45678
example
7890
final9

45678
example
890
final10


SELECT column0, column1, column3, column42
FROM   DT1
WHERE  column1 is null
OR     column1= '0'
OR     column1= 'example'
UNION ALL
SELECT column0, column1, column3, column42
FROM   DT2
WHERE  column42 like 'f%';


COLUMN0
COLUMN1
COLUMN3
COLUMN42


1234
example
345
final1

1234
example
567
final3

1234
example
789
final5

12345
example
7890
final9

12345
example
890
final10

4567
example
345
final1

4567
example
567
final3

4567
example
789
final5

45678
example
7890
final9

45678
example
890
final10


SELECT column0, column1, column3, column42
FROM   DT1
WHERE  column1 is null
OR     column1= '0'
OR     column1= ' '
UNION ALL
SELECT column0, column1, column3, column42
FROM   DT2
WHERE  column3 like '%ff%';

COLUMN0	COLUMN1	COLUMN3	COLUMN42
1234	example	345	final1
1234	example	567	final3
1234	example	789	final5
12345	example	7890	final9
12345	example	890	final10
4567	example	345	final1
4567	example	567	final3
4567	example	789	final5
45678	example	7890	final9
45678	example	890	final10