MySQL 加入 JSON 数组

问题描述

我在 mysql 表中有这些行

I have these rows in mysql table

id  categoryNameSp    categoryNameEn
1   Comida            Food
2   Fruta             Fruit
3   Fruta Seca        Dried fruit

然后我在另一个表中有这一行

And then i have this row in another table

pid  path
1    ["1", "2", "3"]

我想返回路径，但我想返回 categoryNameEn 而不是数字，因此返回将是:

I want to return the path but instead of numbers i want to return categoryNameEn so the return will be:

  pid  path
  1    ["Food","Fruit", "Dried fruit"]

推荐答案

这需要使用 JSON_TABLE 功能以及 JSON_ARRAYAGG 聚合函数.

This would require to use the JSON_TABLE functionality as well as the JSON_ARRAYAGG aggregation function.

使用以下 DML 和 DDL:

CREATE TABLE categories (id INT, name VARCHAR(30));
INSERT INTO categories VALUES (1, 'Food'), (2, 'Fruit'), (3, 'Dried Fruit');

CREATE TABLE stuff (pid INT, path JSON);
INSERT INTO stuff VALUES (1, '["1", "2", "3"]');

然后我们可以做以下(花式)查询:

Then we can do the following (fancy) query:

SELECT pid, JSON_ARRAYAGG(c.name) FROM stuff AS s
    JOIN JSON_TABLE(s.path, '$[*]' COLUMNS (category INT PATH '$')) AS cats
    JOIN categories AS c ON cats.category = c.id
    GROUP BY pid;

这个想法是根据 stuff 表中的 JSON 数据创建一个表.然后我们将它与类别表连接起来，并将结果聚合到一个 JSON 数组中.

The idea is to create a table from the JSON data found in the stuff table. We then join it with the categories tables, and aggregate the result into a JSON array.

结果:

+------+----------------------------------+
| pid  | JSON_ARRAYAGG(c.name)            |
+------+----------------------------------+
|    1 | ["Food", "Fruit", "Dried Fruit"] |
+------+----------------------------------+

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