is null
is null operator is used to test for NULL values, which is equivalent to
the function isNull.
is not null operator is used to test for non-empty values (NOT NULL
values).
The SQL keywords is null/is not null support distributed queries to
access data from DFS tables.
Examples
t= table(`a1`a2`a3`b1`b2`b3`c1`c2 as id, 7 4 NULL 1 8 NULL 12 NULL as val)
select id from t where val is null
// equivalent to `select id from t where isNull(val)`| id |
|---|
| a3 |
| b3 |
| c2 |
select id from t where val is not null
// equivalent to `select id from t where not isNull(val)`| id |
|---|
| a1 |
| a2 |
| b1 |
| b2 |
| c1 |