Multi database support for SQL query

SELECT 
    si.product_id, 
    p.product_name, 
    SUM(si.quantity) AS total_quantity_sold, 
    s.supplier_name
FROM 
    CalMart_Sales_DB.Sales_Items si
JOIN 
    CalMart_Products_DB.Products p 
ON 
    si.product_id = p.product_id
JOIN 
    CalMart_Products_DB.Product_Supplier ps 
ON 
    p.product_id = ps.product_id
JOIN 
    CalMart_Products_DB.Suppliers s 
ON 
    ps.supplier_id = s.supplier_id
GROUP BY 
    si.product_id, p.product_name, s.supplier_name
ORDER BY 
    total_quantity_sold DESC;