Categories:
Conditional Expression Functions

IS [ NOT ] NULL

Determines whether an expression is NULL or is not NULL.

Syntax

<expr> IS [ NOT ] NULL

Returns

Returns BOOLEAN true or false.

Examples

Create and load the table:

CREATE OR REPLACE TABLE i (id NUMBER, col1 NUMBER, col2 NUMBER);
INSERT INTO i (id, col1, col2) VALUES 
    (1, 0, 5), 
    (2, 0, null), 
    (3, null, 5), 
    (4, null, null);

Show the data:

SELECT * 
    FROM i
    ORDER BY id;
+----+------+------+
| ID | COL1 | COL2 |
|----+------+------|
|  1 |    0 |    5 |
|  2 |    0 | NULL |
|  3 | NULL |    5 |
|  4 | NULL | NULL |
+----+------+------+

Use IS NOT NULL:

SELECT * 
    FROM i 
    WHERE col1 IS NOT NULL
    ORDER BY id;
+----+------+------+
| ID | COL1 | COL2 |
|----+------+------|
|  1 |    0 |    5 |
|  2 |    0 | NULL |
+----+------+------+

Use IS NULL:

SELECT * 
    FROM i 
    WHERE col2 IS NULL
    ORDER BY id;
+----+------+------+
| ID | COL1 | COL2 |
|----+------+------|
|  2 |    0 | NULL |
|  4 | NULL | NULL |
+----+------+------+

Use a combination of IS NOT NULL and IS NULL:

SELECT * 
    FROM i 
    WHERE col1 IS NOT NULL OR col2 IS NULL
    ORDER BY id;
+----+------+------+
| ID | COL1 | COL2 |
|----+------+------|
|  1 |    0 |    5 |
|  2 |    0 | NULL |
|  4 | NULL | NULL |
+----+------+------+