Select Information from All Tables
It says like syntax error, which you missed the ,

SELECT
    Customer.CustNo,
    Customer.FirstName,
    Customer.LastName,
    `Order`.OrderNo,
    `Order`.OrderDate,
    Employee.EmpNo,
    Employee.FirstName,
    Employee.LastName,
    Product.ProdNo,
    Product.ProdName,
    CONCAT('$', ProductInOrder.Qty * SUBSTRING(Product.Price, 2)) AS `Order Cost`
From Customer, `Order`, Employee, Product, ProductInOrder
WHERE
    `Order`.Employee_EmpNo IS NOT NULL                          AND
    STR_TO_DATE(`Order`.OrderDate, '%m/%d/%Y') = '2007-1-23'    AND
    `Order`.Cost &gt; 150
ORDER BY `Order`.Cost DESC;