Get Json keys in a MySQL for a particular value

Question

I just installed MySQL 5.7.27 and I would like to use some Json fields so, I created some records, for example this value in a field:

{
  \"Intitule\": {
    \"n         


        

Answer 1

Like i said, it can be a challenge parsing JSON in MySQL as you are dealing with text based keys here.
So you would need to use JSON_KEYS() to get those in combination with a number generator a dynamic JSON path is generated to be used in JSON_EXTRACT()

MySQL 's 8 function JSON_TABLE() makes it much much more easy..

Keep in mind this answer is purely meant for educational fun

Bill Karwin 's comment

You should either structure your JSON differently to support the search you need to do, or else you should not use JSON. Just store the data in multiple rows, and then SELECT * FROM mytable WHERE is_filter = true -

Query

 SELECT
  JSON_UNQUOTE(
    JSON_EXTRACT(json ,  CONCAT('$.', SUBSTRING_INDEX(
       SUBSTRING_INDEX(json_parsed, ',', number_generator.number)
       , ','
       , -1
     ), '.name'))) AS name
FROM (

  SELECT 
   @row := @row + 1 AS number
  FROM (
    SELECT 0 UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION   SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9
  ) row1
  CROSS JOIN (
    SELECT 0 UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION  SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9
  ) row2
  CROSS JOIN (
    SELECT @row := 0 
  ) init_user_params 
) AS number_generator
CROSS JOIN (

    SELECT  
        SUBSTRING(json_keys, 2, json_keys_length - 2) AS json_parsed
      , json_keys
      , json
      , JSON_LENGTH(json_keys) AS json_array_length                       
    FROM (
       SELECT 
            JSON_KEYS(record.json) AS json_keys
          , json
          , LENGTH(JSON_KEYS(record.json)) AS json_keys_length
       FROM (
          SELECT 
             '{
                "Intitule": {
                   "name": "Intitule de la formation",
                   "stats": false,
                   "is_array": false,
                   "is_filter": true,
                   "chart": "pie",
                   "col": "6"
                },
                "Fin": {
                    "name": "Date de fin",
                    "stats": false,
                    "is_array": false,
                    "is_filter": false,
                    "chart": "pie",
                    "col": "6"
                    }
                }' AS json
          FROM  
            DUAL  
       ) AS record                     
    ) AS json_information  
  ) AS json_init
WHERE
   number_generator.number BETWEEN 0 AND json_array_length
 AND
   JSON_EXTRACT(json ,  CONCAT('$.', SUBSTRING_INDEX(
     SUBSTRING_INDEX(json_parsed, ',', number_generator.number)
     , ','
     , -1
   ), '.is_filter')) = true 

Result

| name                     |
| ------------------------ |
| Intitule de la formation |

see demo

Answer 2

This answer is to expand on the comment I made above.

When you store data in non-relational format, you should understand that the structure of the data must serve the queries you need to run. You can't just store any data and expect it to be easy to query.

For example, if you need to search for the subdocument where is_filter is true, then store your JSON like this:

{
  "filter": {
    "label": "Intitule",
    "name": "Intitule de la formation",
    "stats": false,
    "is_array": false,
    "chart": "pie",
    "col": "6"
  },
  "not_filter": {
    "label": "Fin",
    "name": "Date de fin",
    "stats": false,
    "is_array": false,
    "chart": "pie",
    "col": "6"
  }
}

If you need to use a variety of queries against the data, then using non-relational data like JSON is probably not as useful as storing the data in a relational manner.

mysql> select * from mytable;
+----------+--------------------------+-------+----------+-----------+-------+------+
| label    | name                     | stats | is_array | is_filter | chart | col  |
+----------+--------------------------+-------+----------+-----------+-------+------+
| Intitule | Intitule de la formation |     0 |        0 |         1 | pie   |    6 |
| Fin      | Date de fin              |     0 |        0 |         0 | pie   |    6 |
+----------+--------------------------+-------+----------+-----------+-------+------+

Then you can query by any attribute:

SELECT label FROM mytable WHERE is_filter = true;

NoSQL is more flexible than SQL for storing data.

SQL is more flexible than NoSQL for querying data.