Use CopyToDataTable Operator When Primary Keys Are Established
using System; using System.Linq; using System.Collections; using System.Collections.Generic; using System.Data; class Program/* w w w. jav a 2 s.com*/ { static void Main(string[] args) { Student[] students = { new Student { Id = 1, Name = "Joe Ruby" }, new Student { Id = 7, Name = "Apache Python" }, new Student { Id = 13, Name = "Scala CSS" }, new Student { Id = 72, Name = "Django SQL" } }; DataTable dt1 = GetDataTable(students); DataTable newTable = dt1.AsEnumerable().CopyToDataTable(); newTable.PrimaryKey = new DataColumn[] { newTable.Columns[0] }; Console.WriteLine("Before upserting DataTable:"); foreach (DataRow dataRow in newTable.AsEnumerable()) { Console.WriteLine("Student Id = {0} : original {1} : current {2}", dataRow.Field<int>("Id"), dataRow.Field<string>("Name", DataRowVersion.Original), dataRow.Field<string>("Name", DataRowVersion.Current)); } (from s in dt1.AsEnumerable() where s.Field<string>("Name") == "Apache Python" select s).Single<DataRow>().SetField("Name", "C++"); dt1.AsEnumerable().CopyToDataTable(newTable, LoadOption.Upsert); Console.WriteLine("{0}After upserting DataTable:", System.Environment.NewLine); foreach (DataRow dataRow in newTable.AsEnumerable()) { Console.WriteLine("Student Id = {0} : original {1} : current {2}", dataRow.Field<int>("Id"), dataRow.HasVersion(DataRowVersion.Original) ? dataRow.Field<string>("Name", DataRowVersion.Original) : "-does not exist-", dataRow.Field<string>("Name", DataRowVersion.Current)); } } static DataTable GetDataTable(Student[] students) { DataTable table = new DataTable(); table.Columns.Add("Id", typeof(Int32)); table.Columns.Add("Name", typeof(string)); foreach (Student student in students) { table.Rows.Add(student.Id, student.Name); } return (table); } static void OutputDataTableHeader(DataTable dt, int columnWidth) { string format = string.Format("{0}0,-{1}{2}", "{", columnWidth, "}"); // Display the column headings. foreach (DataColumn column in dt.Columns) { Console.Write(format, column.ColumnName); } Console.WriteLine(); foreach (DataColumn column in dt.Columns) { for (int i = 0; i < columnWidth; i++) { Console.Write("="); } } Console.WriteLine(); } } class Student { public int Id; public string Name; }