Look at what kind of function you need, B2B e-commerce site whose database is generally written by programmers, this depends on what technology you need, Java's database is probably more than 5,000 yuan it, PHP is open source technology, probably about 6,000 yuan, such as Maddox B2B e-commerce system of the database design out is about 4,500 yuan it, you can also directly Find this team design.