Топ-100
top of page
Волнистый абстрактный фон
CerebroSQL

->

База данных: MySQL

68747470733a2f2f7374796c65732e7265646469746d656469612e636f6d2f74355f32716d366b2f7374796c65

Topic

Syntax:
column->path

The -> operator serves as an alias for the JSON_EXTRACT() function when
used with two arguments, a column identifier on the left and a JSON
path on the right that is evaluated against the JSON document (the
column value). You can use such expressions in place of column
identifiers wherever they occur in SQL statements.

URL: https://dev.mysql.com/doc/refman/8.0/en/json-search-functions.html

Example

mysql> SELECT c, JSON_EXTRACT(c, "$.id"), g
> FROM jemp
> WHERE JSON_EXTRACT(c, "$.id") > 1
> ORDER BY JSON_EXTRACT(c, "$.name");
+-------------------------------+-----------+------+
| c | c->"$.id" | g |
+-------------------------------+-----------+------+
| {"id": "3", "name": "Barney"} | "3" | 3 |
| {"id": "4", "name": "Betty"} | "4" | 4 |
| {"id": "2", "name": "Wilma"} | "2" | 2 |
+-------------------------------+-----------+------+
3 rows in set (0.00 sec)

mysql> SELECT c, c->"$.id", g
> FROM jemp
> WHERE c->"$.id" > 1
> ORDER BY c->"$.name";
+-------------------------------+-----------+------+
| c | c->"$.id" | g |
+-------------------------------+-----------+------+
| {"id": "3", "name": "Barney"} | "3" | 3 |
| {"id": "4", "name": "Betty"} | "4" | 4 |
| {"id": "2", "name": "Wilma"} | "2" | 2 |
+-------------------------------+-----------+------+
3 rows in set (0.00 sec)

mysql> ALTER TABLE jemp ADD COLUMN n INT;
Query OK, 0 rows affected (0.68 sec)
Records: 0 Duplicates: 0 Warnings: 0

mysql> UPDATE jemp SET n=1 WHERE c->"$.id" = "4";
Query OK, 1 row affected (0.04 sec)
Rows matched: 1 Changed: 1 Warnings: 0

mysql> SELECT c, c->"$.id", g, n
> FROM jemp
> WHERE JSON_EXTRACT(c, "$.id") > 1
> ORDER BY c->"$.name";
+-------------------------------+-----------+------+------+
| c | c->"$.id" | g | n |
+-------------------------------+-----------+------+------+
| {"id": "3", "name": "Barney"} | "3" | 3 | NULL |
| {"id": "4", "name": "Betty"} | "4" | 4 | 1 |
| {"id": "2", "name": "Wilma"} | "2" | 2 | NULL |
+-------------------------------+-----------+------+------+
3 rows in set (0.00 sec)

mysql> DELETE FROM jemp WHERE c->"$.id" = "4";
Query OK, 1 row affected (0.04 sec)

mysql> SELECT c, c->"$.id", g, n
> FROM jemp
> WHERE JSON_EXTRACT(c, "$.id") > 1
> ORDER BY c->"$.name";
+-------------------------------+-----------+------+------+
| c | c->"$.id" | g | n |
+-------------------------------+-----------+------+------+
| {"id": "3", "name": "Barney"} | "3" | 3 | NULL |
| {"id": "2", "name": "Wilma"} | "2" | 2 | NULL |
+-------------------------------+-----------+------+------+
2 rows in set (0.00 sec)

bottom of page