Appendix：Shared and Platform-Specific Keywords Index
精彩片段：
History of the SQL Standard In response to the proliferation of SQL dialects,ANSI published its first SQL stan-dard in 1986 to bring about greater conformity among vendors.This was followedby a second,widely adopted standard in 1989.The International Standards Orga-nization （ISO）also approved the SQL standard.ANSI released one update in1992,known as SQL92 or SQL2,and another in 1999,termed SQL99 or SQL3.The next update,made in 2003,is also referred to as SQL3（or SQL2003）.Whenwe use that term in this book,we are referring to the 2003 revision of thestandard. Each time it revises the SQL standard,ANSI adds new features and incorporatesnew commands and capabilities into the language.For example,the SQL99 stan-dard added a group of capabilities that handled object-oriented datatypeextensions. Whats New in SQL2006 The ANSI standards body that regulates SQL issued a new standard in 2006,inwhich the important major improvements of SQL3 were retained and augmented.The ANSI SQL2006 release was evolutionary over the SQL3 release,but it did notinclude any significant changes to the SQL3 commands and functions that weredescribed in the second edition of this book.Instead,SQL2006 described anentirely new functional area of behavior for the SQL standard.Briefly,SQL2006describes how SQL and XML（the eXtensible Markup Language）interact.Forexample,the SQL2006 standard describes how to import and store XML data in aSQL database,manipulate that data,and then publish the data both in nativeXML form and as conventional SQL data wrapped in XML form.The SQL2006standard provides a means of integrating SQL application code with XQuery,theXML Query Language standardized by the World Wide Web Consortium（W3C）.Because XML and XQuery are disciplines in their own right,they are consideredbeyond the scope of this book and are not covered here. Whats New in SQL2003（SQL3） SQL99 had two main parts,Foundation：1999 and Bindings：1999.The SQL3 Foun-dation section includes all of the Foundation and Bindings standards fromSQL99,as well as a new section called Schemata.The Core requirements of SQL3 did not change from Core SQL99,so the data-base platforms that conformed to Core SQL99 automatically conform to SQL3.Although the Core of SQI_3 has no additions（except for a few new reservedwords）,a number of individual statements and behaviors have been updated ormodified.Because these updates are reflected in the individual syntax descrip-tions of each statement in Chapter 3,we wont spend time on them here.
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