Returns a new MAP containing the specified key-value pairs from an existing MAP.
To identify the key-value pairs to include in the new map, pass in the keys as arguments, or pass in an array containing the keys.
If a specified key isn’t present in the input map, the key is ignored.
Syntax¶MAP_PICK( <map>, <key1> [, <key2>, ... ] ) MAP_PICK( <map>, <array> )
Copy
Arguments¶map
The input map.
key1,key2
One or more keys that identify the key-value pairs to be included in the returned map.
array
An array of keys that identify the key-value pairs to be included in the returned map. You can specify a semi-structured ARRAY or a structured ARRAY.
Returns a new MAP containing some of the key-value pairs from an existing MAP.
Examples¶Create a new map that contains two of the three key-value pairs from an existing map:
SELECT MAP_PICK({'a':1,'b':2,'c':3}::MAP(VARCHAR,NUMBER),'a', 'b')
AS new_map;
Copy
+-----------+
| NEW_MAP |
|-----------|
| { |
| "a": 1, |
| "b": 2 |
| } |
+-----------+
In the previous example, the keys are passed as arguments to MAP_PICK. You can also use an array to specify the keys:
SELECT MAP_PICK({'a':1,'b':2,'c':3}::MAP(VARCHAR,NUMBER), ['a', 'b'])
AS new_map;
Copy
+-----------+
| NEW_MAP |
|-----------|
| { |
| "a": 1, |
| "b": 2 |
| } |
+-----------+
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';
Copy
Query the table to show the data:
+----+---------------------+----------------------+--------------+----------+---------+-----------------+----------+----------+
| 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" | ] | | | | | |
| | | } | | | | | | |
+----+---------------------+----------------------+--------------+----------+---------+-----------------+----------+----------+
Using the keys in the keep_keys column, return new MAP values from the MAP values in the attrs column:
SELECT id, MAP_PICK(attrs, keep_keys) AS attrs_subset FROM demo_maps;
Copy
+----+--------------------+
| ID | ATTRS_SUBSET |
|----+--------------------|
| 1 | { |
| | "brand": "Acme", |
| | "color": "red" |
| | } |
| 2 | { |
| | "brand": "ZenCo" |
| | } |
+----+--------------------+
RetroSearch is an open source project built by @garambo | Open a GitHub Issue
Search and Browse the WWW like it's 1997 | Search results from DuckDuckGo
HTML:
3.2
| Encoding:
UTF-8
| Version:
0.7.4