การใช้ STRING_AGG และ ARRAY_CONCAT_AGG

-- Fill in the query to find the distinct product categories for each order

SELECT
    o.order_id,  
    -- Use the STRING_AGG to find distinct values and separate them by a comma with a space
    ___(___ product_category_name_english, ___) AS categories
FROM
    ecommerce.ecomm_orders o, UNNEST(order_items) items
JOIN
    ecommerce.ecomm_products p ON items.product_id = p.product_id
-- Find the number of items in the order_items column
WHERE ___(o.order_items) > 1
GROUP BY
    order_id