//linq對集合的各種查詢
public static void run()
);customerlist.add(new customers() );
customerlist.add(new customers() );
customerlist.add(new customers() );
customerlist.add(new customers() );
//簡單的查詢
var customerquery = from query in customerlist
select query;
//帶where篩選
var customerwherequery = from query in customerlist
where query.id == 1 && query.name == "lus"
select query;
//排序ordering
var customerorderingquery = from query in customerlist
where query.name == "lus"
orderby query.id ascending
select query;
//分組group by
var customergroupbyquery = from query in customerlist
group query by query.name;
//可以使用into進一步查詢
var customergroupbyintoquery = from query in customerlist
group query by query.name into querygroup
where querygroup.key == "qiao"
select querygroup;
//聯接查詢 join 子句始終針對物件集合而非直接針對資料庫表執行。
list customerjoinlist = new list();
customerjoinlist.add(new customers() );
customerjoinlist.add(new customers() );
customerjoinlist.add(new customers() );
var customerjoinquery = from query1 in customerlist
join query2 in customerjoinlist
on query1.id equals query2.id
select new ;
//資料來源的型別引數始終為查詢中的範圍變數的型別。
//比如list 型別為customers 在迴圈迭代的時候型別必須可以隱式轉換為customer 有一種情況是
//這種情況下customers型別轉換為了string ..在select query.name已經將查詢目標型別定位了string型別
var customertypequery = from query in customerlist
where query.name == "lus"
select query.name;
//結合lamdba對list集合篩選(s => s.name == "qiao")
list liststring = customerlist.where(s => s.name == "qiao").tolist(); }}
public class customers
public string name
public string custom
}
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