Linq查询DataTable,DataRow

最新推荐文章于 2024-11-12 17:48:22 发布

转载最新推荐文章于 2024-11-12 17:48:22 发布 · 1.5k 阅读

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本文演示了如何使用C#中的LINQ查询语法从数据库获取并处理数据。具体包括连接数据库、填充DataTable、筛选偶数ID的数据行及ID大于10的数据行，并进行集合交集操作。

static void Main() 

02        { 

03            string strcon = global::TestLinqToSQL.Properties.Settings.Default.testConnectionString; 

04            SqlConnection conn = new SqlConnection(strcon); 

05            SqlDataAdapter da = new SqlDataAdapter("select * from T_Teacher", strcon); 

06            DataTable dt = new DataTable(); 

07            da.Fill(dt); 

08            conn.Close(); 

09  

10            IEnumerable<DataRow> q1 = from r in dt.AsEnumerable() 

11                                      where r.Field<int>("ID") % 2 == 0 

12                                      select r; 

13            foreach (var item in q1) 

14            { 

15                Console.WriteLine("ID={0},Name={1},Birthday={2}", item["ID"].ToString(), item["Name"].ToString(), item["Birthday"].ToString()); 

16            } 

17            Console.WriteLine("-----------------------------------"); 

18            IEnumerable<DataRow> q2 = from r in dt.AsEnumerable() 

19                                      where r.Field<int>("ID")>10 

20                                      select r; 

21            foreach (var item in q2) 

22            { 

23                Console.WriteLine("ID={0},Name={1},Birthday={2}", item["ID"].ToString(), item["Name"].ToString(), item["Birthday"].ToString()); 

24            } 

25            Console.WriteLine("-----------------------------------"); 

26            DataTable dt1 = q1.CopyToDataTable(); 

27            DataTable dt2 = q2.CopyToDataTable(); 

28            //var except = dt2.AsEnumerable().Except(dt1.AsEnumerable() , DataRowComparer.Default); //集合排除 

29            //var except = dt2.AsEnumerable().Union(dt1.AsEnumerable(), DataRowComparer.Default);   //集合并 

30            var except = dt2.AsEnumerable().Intersect(dt1.AsEnumerable(), DataRowComparer.Default); //集合交 

31            foreach (var item in except) 

32            { 

33                Console.WriteLine("ID={0},Name={1},Birthday={2}", item["ID"].ToString(), item["Name"].ToString(), item["Birthday"].ToString()); 

34            } 

35            Console.WriteLine("done"); 

36            Console.ReadLine(); 

37        }