JSON_MERGE_PATCH()

JSON_MERGE_PATCH(doc…) merges two or more JSON documents following RFC 7396 semantics, in which a null value deletes a member and later objects overwrite earlier values.

Description

JSON_MERGE_PATCH(json [, json] ...) merges the input documents from left to right using RFC 7396 merge-patch semantics:

• Object members from later documents replace earlier members with the same key.

• A member with a null value in a later document removes the corresponding member.

• Arrays and scalar values are replaced wholesale rather than combined.

This differs from JSON_MERGE_PRESERVE(), which combines duplicate keys and array elements instead of overwriting them.

Syntax

JSON_MERGE_PATCH(json [, json] ...)

Arguments

Argument	Description
json	Two or more JSON documents to merge.

Return Value

Returns the merged JSON document.

Examples

DROP DATABASE IF EXISTS json_merge_patch_demo;
CREATE DATABASE json_merge_patch_demo;
USE json_merge_patch_demo;

SELECT JSON_MERGE_PATCH('{"a":1,"b":2}', '{"b":3,"c":4}') AS patched;
SELECT JSON_MERGE_PATCH('{"a":1,"b":2}', '{"b":null}') AS deleted_b;
SELECT JSON_MERGE_PATCH('{"a":{"x":1}}', '{"a":{"y":2}}') AS nested_patch;

DROP DATABASE json_merge_patch_demo;