只是閒來無事對Linq的一些筆記,不是什麼技術分析文章。以簡單的例子來展示Linq之美
1.簡單查詢一個字段(在VS2008中先要新建一個Linq to SQL類).
DataClasses1DataContext db = new DataClasses1DataContext();
var result = from q in db.t_customer
select q.Name; //只查詢表中Name字段
2.匿名類型形式:
DataClasses1DataContext db = new DataClasses1DataContext();
var result = from q in db.t_customer
select new { Name=q.name,Tel=q.tel==""?"00000":q.tel};//其中TEL後面的和SQL語句中的 case when then一樣,還是置換成case when then
3.其中 select new _可以爲指定類型,不過要和查詢的字段類型一樣 (新建一個和查詢結果一樣的類Coutmer)
DataClasses1DataContext db = new DataClasses1DataContext();
var result = from q in db.t_customer
select new Coutmer{ Name=q.name,Tel=q.tel==""?"00000":q.tel};
4Distinct形式(去重複)
DataClasses1DataContext db = new DataClasses1DataContext();
var result = (from q in db.t_customer
select new Coutmer{ Name=q.name,Tel=q.tel==""?"00000":q.tel}).Distinct();