CREATE TABLE t(a INTEGER, ts timestamp time index);

Affected Rows: 0

INSERT INTO t VALUES (1, 1), (null, 2), (3, 3);

Affected Rows: 3

SELECT ISNULL(a) from t;

+-------------+
| isnull(t.a) |
+-------------+
| false       |
| true        |
| false       |
+-------------+

SELECT ISNULL(null);

+--------------+
| isnull(NULL) |
+--------------+
| true         |
+--------------+

SELECT ISNULL(1);

+------------------+
| isnull(Int64(1)) |
+------------------+
| false            |
+------------------+

SELECT ISNULL(-1);

+-------------------+
| isnull(Int64(-1)) |
+-------------------+
| false             |
+-------------------+

SELECT ISNULL(1.0);

+--------------------+
| isnull(Float64(1)) |
+--------------------+
| false              |
+--------------------+

SELECT ISNULL(true);

+-----------------------+
| isnull(Boolean(true)) |
+-----------------------+
| false                 |
+-----------------------+

SELECT ISNULL('string');

+------------------------+
| isnull(Utf8("string")) |
+------------------------+
| false                  |
+------------------------+

SELECT FIRST_VALUE(1);

+-----------------------+
| first_value(Int64(1)) |
+-----------------------+
| 1                     |
+-----------------------+

SELECT FIRST_VALUE('a');

+------------------------+
| first_value(Utf8("a")) |
+------------------------+
| a                      |
+------------------------+

SELECT LAST_VALUE(1);

+----------------------+
| last_value(Int64(1)) |
+----------------------+
| 1                    |
+----------------------+

SELECT LAST_VALUE('a');

+-----------------------+
| last_value(Utf8("a")) |
+-----------------------+
| a                     |
+-----------------------+

DROP TABLE t;

Affected Rows: 0