tailieunhanh - An Introduction to Database Systems 8Ed - C J Date - Solutions Manual Episode 2 Part 9

Tham khảo tài liệu 'an introduction to database systems 8ed - c j date - solutions manual episode 2 part 9', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | To repeat no prior knowledge of XML is needed for this chapter. That s why there are three sections on XML per se this overview section plus the next two on XML data definition and XML data manipulation respectively. Note that there s very little on databases as such in these three sections. However they re definitely written from a database viewpoint They downplay some aspects . namespaces stylesheets that XML aficionados might think are important but database people probably don t at the same time they emphasize others . integrity data types that XML people don t seem to be very interested in but database people are or should be . As a consequence I think you should at least hit the highlights of these three sections even if your audience is already XML-aware. In the case of the present section the highlights are as follows An XML document is a document created using XML facilities loose definition the definition is loose because XML documents are really created using not XML per se but rather some XML derivative XML is really a metalanguage or more precisely a metametalanguage . Explain elements tags note that there s some confusion over the precise meaning of this term attributes empty elements. Note This latter is another misnomer really an empty element is an element that contains an empty character string which isn t the same as being empty which would mean it contains nothing at all and it often has attributes too. Mention development history proprietary and somewhat procedural markup languages such as Script then GML Standard GML HTML XML. XML has not exactly met its original goal of replacing HTML but it has been widely used for other purposes. That s why there s a need to keep XML data in databases. The DRAWING example is worth discussing note the message implicit in that example that an XML document might very reasonably appear in a relational database as an attribute value within some tuple . Definitely discuss the PartsRelation example. Point .

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