SELECT  
    Name, 
    IFNULL(ProductCount, 0) AS Liczebność,
    IFNULL(MinDate, 'Brak danych') AS DATA
FROM 
    productcategory
LEFT JOIN (
    SELECT 
        COUNT(*) AS ProductCount, 
        CategoryId
    FROM 
        product 
    GROUP BY 
        CategoryId
) AS CategoryCount ON CategoryCount.CategoryId = productcategory.Id
LEFT JOIN (
    SELECT 
        MIN(OrderDate) as MinDate,
        product.CategoryId
    FROM 
        orders
    INNER JOIN 
        orderdetails ON orderdetails.OrderId = orders.Id
    INNER JOIN 
        product ON product.Id = orderdetails.ProductId
    GROUP BY 
        product.CategoryId
) AS Orders ON Orders.CategoryId = productcategory.Id;