How to determine if NULL is contained in an array in Postgres?

Question

How do I determine if NULL is contained in an array in Postgres? Currently using Postgres 9.3.3.

If I test with the following select it returns contains_null =

Answer 1

One more construction, like @Clodoaldo Neto proposed. Just more compact expression:

CREATE TEMPORARY TABLE null_arrays (
      id serial primary key
    , array_data int[]
);

INSERT INTO null_arrays (array_data)
VALUES
      (ARRAY[1,2, NULL, 4, 5])
    , (ARRAY[1,2, 3, 4, 5])
    , (ARRAY[NULL,2, 3, NULL, 5])
;

SELECT 
    *
FROM 
    null_arrays
WHERE
    TRUE = ANY (SELECT unnest(array_data) IS NULL)
;

Answer 2

i didn't want to use unnest either, so i used a comparison of array_length using array_remove to solve a similar problem. Tested on 9.4.1, but should work in 9.3.3.

SELECT
ARRAY_LENGTH(ARRAY[1,null], 1) > ARRAY_LENGTH(ARRAY_REMOVE(ARRAY[1,null], NULL), 1) 
OR ARRAY_LENGTH(ARRAY_REMOVE(ARRAY[1,null], NULL), 1) IS NULL
---------
t

Answer 3

select exists (
    select 1 
    from unnest(array[1, null]) s(a)
    where a is null
);
 exists 
--------
 t

Or shorter:

select bool_or(a is null)
from unnest(array[1, null]) s(a)
;
 bool_or 
---------
 t

Answer 4

Ideally you'd write:

SELECT
    NULL IS NOT DISTINCT FROM ANY ARRAY[NULL,1,2,3,4,NULL]::int[];

but the parser doesn't recognise IS NOT DISTINCT FROM as valid syntax for an operator here, and I can't find an operator alias for it.

You'd have to:

CREATE FUNCTION opr_isnotdistinctfrom(anyelement, anyelement)
RETURNS boolean LANGUAGE SQL IMMUTABLE AS $$
SELECT $1 IS NOT DISTINCT FROM $2; 
$$;

CREATE OPERATOR <<>> (
    PROCEDURE = opr_isnotdistinctfrom,
    LEFTARG = anyelement,
    RIGHTARG = anyelement
);

SELECT NULL <<>> ANY (ARRAY[NULL,1,2,3,4,NULL]::int[]);

which seems a bit gruesome, but should optimize out just fine.

Answer 5

It seems the following works fine in PostgreSQL 10.1.

CREATE TABLE my_table
(
    ...
    my_set  int[] NOT NULL,
    ...
);

SELECT
    my_set
FROM
    my_table
WHERE
    array_position(my_set, NULL) IS NOT NULL;