Purpose
Merges two or more JSON documents and returns the merged result.
Syntax
JSON_MERGE_PRESERVE(json_doc, json_doc[, json_doc] ...)
Parameters
The json_doc parameter specifies the JSON documents to be merged.
If any parameter is NULL, NULL is returned. If any parameter is not a valid JSON document, an error is returned.
The merging rules of JSON_MERGE_PRESERVE() are as follows:
Adjacent arrays are merged into one array.
Adjacent objects are merged into one object.
Scalar values are automatically wrapped into arrays and merged into arrays.
Adjacent arrays and objects are merged by wrapping objects into arrays.
Examples
obclient> SELECT JSON_MERGE_PRESERVE('[1, 2, 3]', '[true, false]');
+---------------------------------------------------+
| JSON_MERGE_PRESERVE('[1, 2, 3]', '[true, false]') |
+---------------------------------------------------+
| [1, 2, 3, true, false] |
+---------------------------------------------------+
1 row in set
obclient> SELECT JSON_MERGE_PRESERVE('{"name": "apple"}', '{"id": 56}');
+--------------------------------------------------------+
| JSON_MERGE_PRESERVE('{"name": "apple"}', '{"id": 56}') |
+--------------------------------------------------------+
| {"id": 56, "name": "apple"} |
+--------------------------------------------------------+
1 row in set
obclient> SELECT JSON_MERGE_PRESERVE('1', 'true');
+----------------------------------+
| JSON_MERGE_PRESERVE('1', 'true') |
+----------------------------------+
| [1, true] |
+----------------------------------+
1 row in set
obclient> SELECT JSON_MERGE_PRESERVE('[1, 2, 3]', '{"id": 56}');
+------------------------------------------------+
| JSON_MERGE_PRESERVE('[1, 2, 3]', '{"id": 56}') |
+------------------------------------------------+
| [1, 2, 3, {"id": 56}] |
+------------------------------------------------+
1 row in set
obclient> SELECT JSON_MERGE_PRESERVE('{ "a": 1, "b": 2, "c": 5}', '{ "a": 3, "c": 4 }');
+-------------------------------------------------------------------------+
| JSON_MERGE_PRESERVE('{ "a": 1, "b": 2, "c": 5}', '{ "a": 3, "c": 4 }') |
+-------------------------------------------------------------------------+
| {"a": [1, 3], "b": 2, "c": [5, 4]} |
+-------------------------------------------------------------------------+
1 row in set
obclient> SELECT JSON_MERGE_PRESERVE('{ "a": 1, "b": 2 }','{ "a": 3, "c": 4 }', '{ "a": 5, "d": 6 }');
+--------------------------------------------------------------------------------------+
| JSON_MERGE_PRESERVE('{ "a": 1, "b": 2 }','{ "a": 3, "c": 4 }', '{ "a": 5, "d": 6 }') |
+--------------------------------------------------------------------------------------+
| {"a": [1, 3, 5], "b": 2, "c": 4, "d": 6} |
+--------------------------------------------------------------------------------------+
1 row in set