Categories:

Semi-structured and structured data functions (Map)

MAP_DELETE

Returns a MAP based on an existing MAP with one or more keys removed.

Syntax

MAP_DELETE( <map>, <key1> [, <key2>, ... ] )
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Arguments

map

The map that contains the key to remove.

keyN

The key to be omitted from the returned map.

Returns

Returns a MAP that contains the contents of the input (source) map with one or more keys removed.

Usage notes

  • The type of the key expression must match the type of the map’s key. If the type is VARCHAR, then the types can be different lengths.

  • Key values that aren’t found in the map are ignored.

Examples

Remove two key-value pairs from a map containing three key-value pairs:

SELECT MAP_DELETE({'a':1,'b':2,'c':3}::MAP(VARCHAR,NUMBER),'a','b');
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+--------------------------------------------------------------+ | MAP_DELETE({'A':1,'B':2,'C':3}::MAP(VARCHAR,NUMBER),'A','B') | |--------------------------------------------------------------| | { | | "c": 3 | | } | +--------------------------------------------------------------+

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';
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Query the table to show the data:

SELECT * FROM demo_maps;
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+----+---------------------+----------------------+--------------+----------+---------+-----------------+----------+----------+ | 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" | ] | | | | | | | | | } | | | | | | | +----+---------------------+----------------------+--------------+----------+---------+-----------------+----------+----------+

Remove the keys in the del_key1 and del_key2 columns from the MAP values in the attrs column:

SELECT id, MAP_DELETE(attrs, del_key1, del_key2) AS attrs_after_delete FROM demo_maps;
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+----+---------------------+ | ID | ATTRS_AFTER_DELETE | |----+---------------------| | 1 | { | | | "color": "red" | | | } | | 2 | { | | | "brand": "ZenCo", | | | "color": "blue" | | | } | +----+---------------------+
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