嵌入式sql语句将unit表中的主管姓名强制转换为xml类型(本例中为xml字符串)，然后将其提供给XQuery。
The embedded SQL statement casts the manager names in the unit table into an XML type (in this case into an XML string), and feeds them into the XQuery.
泛型相当有用，因为他们提供强制的编译时类型检查，要求更少的数据类型之间的显式转换，并减少装箱拆箱的操作和运行时类型检查。
Generics are useful because they provide stronger compile-time type checking, require fewer explicit conversions between data types, and reduce the need for boxing operations and run-time type checks.
当我们显式地提供强制类型转换时，警告信息就会被关闭。
When we provide the explicit cast, the warning message is turned off.
当我们显式地提供强制类型转换时，警告信息就会被关闭。
When we provide the explicit cast, the warning message is turned off.
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