DataTable Linq Group Count where写法

    DataTable dataTable = new DataTable();

    dataTable.Columns.Add("username", typeof(string));

    dataTable.Rows.Add("zgj");

    dataTable.Rows.Add("zgj");

    dataTable.Rows.Add("zgj1");

    dataTable.Rows.Add("zgj1");

    dataTable.Rows.Add("zgj1");

    var query = from t in dataTable.AsEnumerable()

                group t by new { t1 = t.Field<string>("username") } into m

                select new

                {

                    username = m.Key.t1,

                    usernamecount = m.Count()

                };

    foreach (var q in query)

    {

        Console.WriteLine(q.username + ":" + q.usernamecount);

    }

输出结果

zgj:2
zgj1:3

带where 语句写法

var query = from t in dataTable.AsEnumerable()

            where t["username"].ToString()=="zgj"

            group t by new { t1 = t.Field<string>("username") } into m

            select new

            {

                username = m.Key.t1,

                usernamecount = m.Count()

            };