Oracle 18c

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CREATE TABLE test_table (
id number(10),
text_col varchar2(10)
);
INSERT INTO test_table (id, text_col)
VALUES (1, null);
1 rows affected

INSERT INTO test_table (id, text_col)
VALUES (2, '');
1 rows affected

INSERT INTO test_table (id, text_col)
VALUES (3, ' ');
1 rows affected

SELECT * FROM test_table;


ID
TEXT_COL


1
null

2
null

3
 

ID	TEXT_COL
1	null
2	null
3