MAP_FROM_ENTRIES

Description

The MAP_FROM_ENTRIES function is used to create a map type from an array. The elements of the input array need to conform to the format of the map_entries function, where each element is a struct containing key and value properties.

Parameters

• array: Input parameter, type array<struct<key:K, value:V>>, representing an array containing multiple structs, each with key and value properties.

Return Value

Returns a result of type map<K, V>, where K represents the type of the key and V represents the type of the value.

Example Usage

1. Create an array containing two elements, each of which is a struct with two properties: key and value.

SELECT MAP_FROM_ENTRIES(ARRAY(
NAMED_STRUCT('key',1, 'value','a'),
NAMED_STRUCT('key',2, 'value','b')
));

Return Results:

{
  1:"a",
  2:"b"
}

2. Create an array containing three elements, where the element type is a structure, and the structure contains different types of keys and values.

SELECT MAP_FROM_ENTRIES(ARRAY(
NAMED_STRUCT('key',1, 'value','apple' ),
NAMED_STRUCT('key',2, 'value','carrot'),
NAMED_STRUCT('key',3, 'value','dog')
));

Return Results:

{
  1:"apple",
  2:"carrot",
  3:"dog"
}

Note: In the above example, the extra attribute will not be included in the final map because we only care about the key and value attributes.

Notes

• Each struct in the input array must have key and value attributes, otherwise the function will fail.
• The type of the key needs to be unique, and there cannot be duplicate key values, otherwise the later key values will overwrite the earlier key values.