MySQL select last key with value JSON - mysql

Question

I have JSON like:
{"1": "6", "2": "10", "3": "12"}
And i would like to get LAST key and value using MySQL query to get output like:
3x12
3 is the last key, and 12 is the last key value...
Is there any MySQL query to do that? I know using reading whole MySQL filed value as posted above and then while loop and if key is last print its value and key...but if is possible in MySQL query to get this output?
I im using this php that reads MySQL field value and get last key and value...but i don't know how to do it in mysql:
$json = json_decode('{"1": "6", "2": "10", "3": "12"}', true);
$value = end($json);
$key = key($json);
echo 'KEY: '.$key.'...VALUE: '.$value;

Answer 1

You can try something like the following, adjust as necessary:
mysql> SELECT VERSION();
+-----------+
| VERSION() |
+-----------+
| 5.7.20 |
+-----------+
1 row in set (0.00 sec)
mysql> SET #`json` := '
'> {
'> "1": "6",
'> "2": "10",
'> "3": "12"
'> }
'> ';
Query OK, 0 rows affected (0.00 sec)
mysql> SELECT
-> CONCAT(
-> JSON_UNQUOTE(#`key`),
-> 'x',
-> JSON_UNQUOTE(
-> JSON_EXTRACT(#`json`,
-> CONCAT('$.', #`key`)
-> )
-> )
-> ) `value`
-> FROM (
-> SELECT #`key` := JSON_EXTRACT(
-> JSON_KEYS(#`json`),
-> CONCAT('$[', JSON_LENGTH(#`json`) - 1, ']')
-> )
-> ) `init`;
+-------+
| value |
+-------+
| 3x12 |
+-------+
1 row in set (0.00 sec)
See db-fiddle.