OBJECT_CONSTRUCT_KEEP_NULL¶

Syntax¶

OBJECT_CONSTRUCT_KEEP_NULL( [<key1>, <value1> [, <keyN>, <valueN> ...]] )

OBJECT_CONSTRUCT_KEEP_NULL( * )

Returns¶

The data type of the returned value is OBJECT.

Usage Notes¶

• The function accepts either:

  • A sequence of zero or more key-value pairs (where keys are strings, and values are of any type).

  • An asterisk.

  When invoked with an asterisk, the object is constructed using the attribute names as keys and the associated tuple values as values. See the examples below.

• If the key is NULL (i.e. SQL NULL), the key-value pair is omitted from the resulting object. However, if the value is null, then the key-value pair is kept.

• The constructed object does not necessarily preserve the original order of the key-value pairs.

Examples¶

This example shows the difference between OBJECT_CONSTRUCT and OBJECT_CONSTRUCT_KEEP_NULL:

SELECT OBJECT_CONSTRUCT('key_1', 'one', 'key_2', NULL) AS WITHOUT_KEEP_NULL,
       OBJECT_CONSTRUCT_KEEP_NULL('key_1', 'one', 'key_2', NULL) AS KEEP_NULL_1,
       OBJECT_CONSTRUCT_KEEP_NULL('key_1', 'one', NULL, 'two') AS KEEP_NULL_2
       ;
+-------------------+-------------------+------------------+
| WITHOUT_KEEP_NULL | KEEP_NULL_1       | KEEP_NULL_2      |
|-------------------+-------------------+------------------|
| {                 | {                 | {                |
|   "key_1": "one"  |   "key_1": "one", |   "key_1": "one" |
| }                 |   "key_2": null   | }                |
|                   | }                 |                  |
+-------------------+-------------------+------------------+

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The following example also shows the difference between OBJECT_CONSTRUCT and OBJECT_CONSTRUCT_KEEP NULL, but this example uses a small table (which is shown prior to the query):

SELECT *
    FROM demo_table_1
    ORDER BY province;
+------------------+--------------+
| PROVINCE         | CREATED_DATE |
|------------------+--------------|
| Alberta          | 2020-01-19   |
| British Columbia | NULL         |
| Manitoba         | 2020-01-18   |
| NULL             | 2020-01-20   |
+------------------+--------------+

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SELECT OBJECT_CONSTRUCT(*) AS oc,
       OBJECT_CONSTRUCT_KEEP_NULL(*) AS oc_keep_null
    FROM demo_table_1
    ORDER BY oc_keep_null['PROVINCE'];
+----------------------------------+----------------------------------+
| OC                               | OC_KEEP_NULL                     |
|----------------------------------+----------------------------------|
| {                                | {                                |
|   "CREATED_DATE": "2020-01-19",  |   "CREATED_DATE": "2020-01-19",  |
|   "PROVINCE": "Alberta"          |   "PROVINCE": "Alberta"          |
| }                                | }                                |
| {                                | {                                |
|   "PROVINCE": "British Columbia" |   "CREATED_DATE": null,          |
| }                                |   "PROVINCE": "British Columbia" |
|                                  | }                                |
| {                                | {                                |
|   "CREATED_DATE": "2020-01-18",  |   "CREATED_DATE": "2020-01-18",  |
|   "PROVINCE": "Manitoba"         |   "PROVINCE": "Manitoba"         |
| }                                | }                                |
| {                                | {                                |
|   "CREATED_DATE": "2020-01-20"   |   "CREATED_DATE": "2020-01-20",  |
| }                                |   "PROVINCE": null               |
|                                  | }                                |
+----------------------------------+----------------------------------+

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For examples that use the closely-related function OBJECT_CONSTRUCT, see OBJECT_CONSTRUCT.