Categories:: Semi-structured and structured data functions (Map)

MAP_CONTAINS_KEY¶

Determines whether the specified MAP contains the specified key.

Syntax¶

MAP_CONTAINS_KEY( <key> , <map> )

Arguments¶

key: The key to find.
map: The map to be searched.

Returns¶

Returns TRUE if the specified map contains the specified key.
Returns FALSE if the specified map doesn’t contain the specified key.

Usage notes¶

The type of the key expression must match the type of the map’s key. If the type is VARCHAR, the types can be different lengths.
For NULL input, the output is NULL.

Examples¶

The function searches for the k1 key and finds it in the map:

SELECT MAP_CONTAINS_KEY(
  'k1',{'k1':'v1','k2':'v2','k3':'v3'}::MAP(VARCHAR,VARCHAR))
  AS contains_key;

+--------------+
| CONTAINS_KEY |
%--------------%
| True         |
+--------------+

The function searches for the k1 key and doesn’t find it in the map:

SELECT MAP_CONTAINS_KEY(
  'k1',{'ka':'va','kb':'vb','kc':'vc'}::MAP(VARCHAR,VARCHAR))
  AS contains_key;

+--------------+
| CONTAINS_KEY |
%--------------%
| False        |
+--------------+

A SELECT statement passes in a key that uses a different type than the key in the map:

SELECT MAP_CONTAINS_KEY(
  'k1',{'1':'va','2':'vb','3':'vc'}::MAP(NUMBER,VARCHAR))
  AS contains_key;

001065 (22023): SQL compilation error:
Function MAP_CONTAINS_KEY cannot be used with arguments of types VARCHAR(2) and MAP(NUMBER(38,0), VARCHAR(134217728))

Create a temporary table that contains MAP values:

CREATE OR REPLACE TEMP TABLE demo_maps(
  id INTEGER,
  attrs MAP(VARCHAR, VARCHAR),
  defaults MAP(VARCHAR, VARCHAR),
  keep_keys ARRAY(VARCHAR),
  ins_key VARCHAR,
  ins_val VARCHAR,
  update_existing BOOLEAN,
  del_key1 VARCHAR,
  del_key2 VARCHAR);

INSERT INTO demo_maps SELECT
  1,
  {'color':'red','size':'M','brand':'Acme'}::MAP(VARCHAR, VARCHAR),
  {'currency':'USD','size':'L'}::MAP(VARCHAR, VARCHAR),
  ['color','brand']::ARRAY(VARCHAR),
  'material',
  'cotton',
  TRUE,
  'size',
  'brand';

INSERT INTO demo_maps SELECT
  2,
  {'color':'blue','brand':'ZenCo'}::MAP(VARCHAR, VARCHAR),
  {'currency':'EUR','size':'M','brand':'ZenCo'}::MAP(VARCHAR, VARCHAR),
  ['brand','currency']::ARRAY(VARCHAR),
  'brand',
  'ZC',
  FALSE,
  'currency',
  'material';

Query the table to show the data:

SELECT * FROM demo_maps;

+----+---------------------+----------------------+--------------+----------+---------+-----------------+----------+----------+
| ID | ATTRS               | DEFAULTS             | KEEP_KEYS    | INS_KEY  | INS_VAL | UPDATE_EXISTING | DEL_KEY1 | DEL_KEY2 |
|----+---------------------+----------------------+--------------+----------+---------+-----------------+----------+----------|
|  1 | {                   | {                    | [            | material | cotton  | True            | size     | brand    |
|    |   "brand": "Acme",  |   "currency": "USD", |   "color",   |          |         |                 |          |          |
|    |   "color": "red",   |   "size": "L"        |   "brand"    |          |         |                 |          |          |
|    |   "size": "M"       | }                    | ]            |          |         |                 |          |          |
|    | }                   |                      |              |          |         |                 |          |          |
|  2 | {                   | {                    | [            | brand    | ZC      | False           | currency | material |
|    |   "brand": "ZenCo", |   "brand": "ZenCo",  |   "brand",   |          |         |                 |          |          |
|    |   "color": "blue"   |   "currency": "EUR", |   "currency" |          |         |                 |          |          |
|    | }                   |   "size": "M"        | ]            |          |         |                 |          |          |
|    |                     | }                    |              |          |         |                 |          |          |
+----+---------------------+----------------------+--------------+----------+---------+-----------------+----------+----------+

Determine whether the map in the attrs column contains the key in the ins_key column:

SELECT id, MAP_CONTAINS_KEY(ins_key, attrs) AS has_key
  FROM demo_maps;

+----+---------+
| ID | HAS_KEY |
|----+---------|
|  1 | False   |
|  2 | True    |
+----+---------+

The output shows the following:

The map in the attrs column in row 1 doesn’t contain the key (material) in the ins_key column.
The map in the attrs column in row 2 contains the key (brand) in the ins_key column.