如何从 MariaDB 或 MySQL 中的 JSON 数组中提取值？

Question

Situation

I have a table in a MariaDB database. This table has a LONGTEXT column which is used to store a JSON array (read more about this topic in MariaDB JSON Data Type ).

Question

I would like to extract values from the JSON array, based on a certain key. How do I achieve this with MariaDB (or MySQL)?

Example

Here's the simplified table thing (just for demo purposes):

id	thing_name	examples
0	fruit	[{"color": "green","title": "Apple"},{"color": "orange","title": "Orange"},{"color": "yellow","title": "Banana"}]
1	car	[{"color": "silver","title": "VW"},{"color": "black","title": "Bentley"},{"color": "blue","title": "Tesla"}]

My goal is to extract all title values from the JSON array.

Answer 1

You can use JSON_EXTRACT for this task (works for both MariaDB and MySQL). This function also supports wildcards , as described in the docs:

Paths can contain * or ** wildcards

Depending on whether you have multiple levels of data (eg single document vs array), either a single or double asterisk wildcard should be used:

JSON_EXTRACT(json,'$**.key')

json is a valid JSON document (eg a column), key is the lookup key used.

For your example

In order to find all title values in your JSON array, use the following query:

SELECT id, thing_name, JSON_EXTRACT(examples, '$**.title') as examples_titles FROM thing

id	thing_name	examples_titles
0	fruit	["Apple", "Orange", "Banana"]
1	car	["VW", "Bentley", "Tesla"]