MariaDB动态列嵌套

Question

I have been searching for this for a couple of hours. I have setup a MariaDB server and am implementing Dynamic Columns, which I know how to do, but I can't seem to find out how to go more than one level deep.

INSERT INTO Invoices (Invoice) VALUES (
    COLUMN_CREATE ('Monthly Fee', 500)
);

This works, but what I need is something that will allow me to have something like the following SELECT for JSON:

{
    "services": {
        "Monthly Fee": 500,
        "OnSite": {
            "Units": 10,
            "Rate": 35
        },
        "Mileage": {
            "Units": 181.8,
            "Rate": 0.5
        },
        "Hard Drive Purchase": {
            "Units": 1,
            "Rate": 68.99
        }
    }
}

I just can't figure out how to get the value of the key to be another dynamic column with its own key:value pairs.

I have tried:

INSERT INTO Invoices (Invoice) VALUES (
    COLUMN_CREATE ('Monthly Fee', 500,
        'OnSite',
        COLUMN_CREATE('Units',10,'Rate','35')
    )
);

with nesting where I need it. I'm hoping this is possible and that I just have a simple syntax error.

Any help would be greatly appreciated.

Answer 1

For anyone that might be trying to figure this out:

It was a syntax error. The following syntax gives me what I needed:

SET @tmp = column_create (
    'services',
    column_create (
        'RMM',
        column_create ('Rate', 650),
        'OnSite',
        column_create ('Units', 10, 'Rate', 35),
        'Mileage',
        column_create ('Units', 181.8, 'Rate', 0.50),
        'Hard Drive Purchase',
        column_create ('Units', 1, 'Rate', 68.99)
    )
);

SELECT
    COLUMN_JSON (@tmp);