Tiếp tục, bây giờ bạn nhìn thấy một yếu tố lồng nhau được gọi là khách hàng, có thẻ bắt đầu và kết thúc thẻ. Yếu tố chính nó chứa hai yếu tố lồng nhau, được biết đến như Tên, và được biết đến như nhận dạng. Nó cũng chứa một yếu tố lồng nhau được gọi là hướng dẫn. Yếu tố này và những lồng nhau bên trong nó xuất hiện được một chút bối rối, mặc dù. | 320 Part VI Creating SQL Server 2005 Express Applications reg Duties Not subject to duties reg Duties reg Instructions Customer Continuing you now see a nested element known as Customer whose start tag is Customer and end tag is Customer . This element itself contains two nested elements one known as Name and the other known as Identifier. It also contains a nested element known as Instructions. This element and those nested within it appear to be a little confusing though. What s going on Looking at the XML document listed earlier in the chapter you may wonder how your computer can keep things straight when handling XML received from different sources. For example what happens if you receive purchase orders from two different organizations that use different element names and attributes that actually mean the same thing Conversely what happens if they use identical element names and attributes that mean different things This situation is where namespaces comes to the rescue. Typically available for consultation and review via the Internet namespaces are assemblages of element type and attribute names that help establish order and clear up confusion. By providing a solid point of reference they also assist when merging smaller subsets of XML documents. In this case the document includes a link to a namespace server reg Instructions xmlns reg http importexport By specifying this namespace server any applications that use this XML document consult the namespace server for details about any elements or attributes prefixed with reg. A second namespace server comes up a little later in the XML. Creator Michael McManus Creator Here s an example of an element that tracks the purchase order s creator. It has no nested elements within it is however nested within the purchase order element itself. Product quantity 1 Product quantity 6 price GG2911 Product price TK3020 Product Now you can see additional elements both known as Product. These
