Mikhail Gorbachev's policies of glasnost and perestroika had profound and unintended effects on the Soviet Union. In fact, many historians suggest these reforms led directly to the fall of communism and the breakup of the Soviet Union.
In SQL Server, you create a surrogate key by assigning an identity property to a column that has a number data type. A natural key is a naturally occurring descriptor of the data and one of a table's attributes that has no duplicate values. When you use a natural key as a table's primary key, each of the table's rows is uniquely identified.
The exist() method in the WHERE clause returns 1 (True) if the XML does not include any <Specifications> element. Note the use of the not() function (XQuery). The sql:column() function (XQuery) function is used to bring in the value from a non-XML column. This query returns an empty rowset. The query specifies query() and exist() methods of the xml data type and both these methods declare the same namespaces in the query prolog. In this case, you may want to use WITH XMLNAMESPACES to declare the prefix and use it in the query.