MAP_CONCAT

Description

The MAP_CONCAT function is used to merge key-value pairs from multiple map type parameters into a new map. This function is very useful when dealing with multiple data sources and needing to integrate their data into a single data structure.

Syntax

MAP_CONCAT(map1, map2, ..., mapN)

Parameter Description

• map1 ~ mapN: Input map type parameters, which can be two or more. Each parameter is of type map<K, V>, where K represents the type of the key and V represents the type of the value.

Return Type

Returns a new map<K, V> type that contains all the key-value pairs from the input map parameters.

Example

1. Basic usage:

SELECT MAP_CONCAT(map('key1', 'value1'), map('key2', 'value2'));
// Return result: {"key1":"value1","key2":"value2"}

In this example, two map are merged into one, containing two key-value pairs.

2. Merging multiple parameters:

SELECT MAP_CONCAT(map('a', 1), map('b', 2), map('c', 3));
// Returns result: {"a":1,"b":2,"c":3}

Three map are merged into one, forming a new map containing three key-value pairs.

3. Handling of duplicate keys:

SELECT MAP_CONCAT(map('key', 'original'), map('key', 'override'));
// Return result: {"key":"override"}

When multiple map contain the same key, the value in the latter map will overwrite the value in the former map.