Query Statement 2

Topic: VS custom settings, use macro to solve repetitive work, refer to: http://www.diybl.com/course/4_webprogram/asp.net/netjs/20100714/445361.html

Keyword in the query statement:

Clause	Description
from	Specify the data source and range variables (similar to iteration variables ).
where	Filter source elements based on one or more boolean expressions separated by the logical "and" or "Operator (& |.
select	Specifies the type and format of the elements in the returned sequence when the query is executed.
group	The query results are grouped by the specified key value.
into	Provides an identifier that can be used as a reference to the results of join, group, or select clauses.
orderby	The default comparator of the element type sorts the query results in ascending or descending order.
join	Connect two data sources based on the equal comparison between the two specified matching conditions.
let	Introduce a range variable used to store the results of the subexpression in the query expression.
in	Context keyword in the join clause.
on	Context keyword in the join clause.
equals	Context keyword in the join clause.
by	Context keyword in the group clause.
ascending	The context keyword in the orderby clause.
descending	The context keyword in the orderby clause.