How to tabulate a JSON document in MySQL

- 2 minutes read - 388 words

You can tabulate a JSON document (retrieve it as a row) in MySQL with the JSON_TABLE function.

NOTE: more info is available in the MySQL JSON functions documentation page

 

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The dataset

The dataset is the following:

{
    "id": 778,
    "shop": "Luigis Pizza",
    "name": "Edward Olson",
    "phoneNumbers":
        ["(935)503-3765x4154","(935)12345"],
    "address": "Unit 9398 Box 2056 DPO AP 24022",
    "image": null,
    "pizzas": [
        {
            "pizzaName": "Salami",
            "additionalToppings": ["🥓", "🌶️"]
        },
        {
            "pizzaName": "Margherita",
            "additionalToppings": ["🍌", "🌶️", "🍍"]
        }
    ]
}
Check out the description of the fields The following examples use a pizza order dataset with an order having:
  • id: 778
  • shop: “Luigis Pizza”
  • name: “Edward Olson”
  • phoneNumbers:["(935)503-3765x4154","(935)12345"]
  • address: “Unit 9398 Box 2056 DPO AP 24022”
  • image: null
  • and two pizzas contained in the pizzas item:
[
    {
        "pizzaName": "Salami",
        "additionalToppings": ["🥓", "🌶️"]
    },
    {
        "pizzaName": "Margherita",
        "additionalToppings": ["🍌", "🌶️", "🍍"]
    }
]
If you want to reproduce the examples, check how to recreate the dataset

It can be recreated with the following script:

create table test(id serial primary key, json_data json);

insert into test(json_data) values (
'{
    "id": 778,
    "shop": "Luigis Pizza",
    "name": "Edward Olson",
    "phoneNumbers":
        ["(935)503-3765x4154","(935)12345"],
    "address": "Unit 9398 Box 2056 DPO AP 24022",
    "image": null,
    "pizzas": [
        {
            "pizzaName": "Salami",
            "additionalToppings": ["🥓", "🌶️"]
        },
        {
            "pizzaName": "Margherita",
            "additionalToppings": ["🍌", "🌶️", "🍍"]
        }
    ]
}');

Tabulate a JSON document with JSON_TABLE function

To retrieve one or more JSON documents as columns and rows you can use the JSON_TABLE function. To retrieve the list of pizzas and their first additional topping from the above as table you can:

select tbl.* from
    test, 
    JSON_TABLE(
        json_data,
        '$.pizzas[*]' 
        COLUMNS (
            pizzaName VARCHAR(100) PATH '$.pizzaName', 
            additionalToppings VARCHAR(100) PATH '$.additionalToppings[0]'
            )
        ) tbl;

Where

  • json_data is the JSON column
  • '$.pizzas[*]' generates a row for each pizza in the pizzas array
  • pizzaName VARCHAR(100) PATH '$.pizzaName' retrieves the pizzaName field
  • additionalToppings VARCHAR(100) PATH '$.additionalToppings[0]' retrieves the first element ([0]) of the additionalToppings array

Result

+------------+--------------------+
| pizzaName  | additionalToppings |
+------------+--------------------+
| Salami     | 🥓                 |
| Margherita | 🍌                 |
+------------+--------------------+

Review all the JSON MySQL use-cases listed in the main page