Oracle Database Handling NULL values Columns of any data type can contain NULLs
Example
SELECT 1 NUM_COLUMN, 'foo' VARCHAR2_COLUMN from DUAL
UNION ALL
SELECT NULL, NULL from DUAL;
| NUM_COLUMN | VARCHAR2_COLUMN |
|---|---|
| 1 | foo |
| (null) | (null) |
SELECT 1 NUM_COLUMN, 'foo' VARCHAR2_COLUMN from DUAL
UNION ALL
SELECT NULL, NULL from DUAL;
| NUM_COLUMN | VARCHAR2_COLUMN |
|---|---|
| 1 | foo |
| (null) | (null) |
