Add columns to DataTable

static void Main(string[] args)
{

DataTable dt = new DataTable();

// Add the column to the DataTable to create
DataColumn col1 = dt.Columns.Add();

// Configure the column
//-- integer with a default = 0
// that  does not allow nulls
col1.ColumnName = "1Column";
col1.DataType = typeof(int);
col1.DefaultValue = 0;
col1.Unique = true;
col1.AllowDBNull = false;

// Create  the column
DataColumn col2 = new DataColumn();

// Configure the column
//string with max length = 50
col2.ColumnName = "2Column";
col2.DataType = typeof(string);
col2.MaxLength = 50;


// Add column to the DataTable
dt.Columns.Add(col2);

// Add a column directly using an overload of the Add()
 // method of the DataTable.Columns collection -- the column
 // is a string with max length = 50
dt.Columns.Add("3Column", typeof(string)).MaxLength = 50;

// Add multiple existing columns to the DataTable
DataColumn col4 = new DataColumn("4Column");

// ... configure column 5
DataColumn col5 = new DataColumn("5Column", typeof(int));

// Add columns 4 and 5 to the DataTable
dt.Columns.AddRange(new DataColumn[] { col4, col5 });

// Show the columns in the DataTable to the console
Console.WriteLine("DataTable has {0} DataColumns named:",dt.Columns.Count);

foreach (DataColumn col in dt.Columns)

Console.WriteLine("\t{0}", col.ColumnName);
Console.WriteLine("\nPress any key to continue.");
Console.ReadKey();
}

Table Mapping in DOT.NET

static void Main(string[] args)
{

// Configure Sql Provider - to connect to server or database
  string sqlConnectString = @"Data Source=(local)\sqlexpress;" +
  "Integrated security=SSPI; Initial Catalog=DataBase;";

// Creating a table Cliente in a DataBase (Sql, Access...)

 // Query to get desired data
  String sqlSelect = "SELECT TOP 5 IDCliente,Apelido,PrimNome " +
  "From Cliente";

 //Get data from sql to adapter
  SqlDataAdapter da = new SqlDataAdapter(sqlSelect, sqlConnectString);

//Mappeding the table
  DataTableMapping dtm =da.TableMappings.Add("Table", "mappedCliente");

// Mapping the column
  dtm.ColumnMappings.Add("IDCliente", "mappedIDCliente");
  dtm.ColumnMappings.Add("Apelido", "mappedApelido"); //...

   dtm.ColumnMappings.Add("PrimNome", "mappedPrimNome"); //...

 // (DataSet = DataBase Virtual)
  DataSet ds = new DataSet();

 // dataset get data from adapter 
   da.Fill(ds);
  Console.WriteLine("DataTable name = {0}",ds.Tables[0].TableName);

// show the mapped columns
 foreach (DataColumn col in ds.Tables["mappedCliente"].Columns)

  {
   Console.WriteLine("\tDataColumn {0} name = {1}",col.Ordinal, col.ColumnName);
  }

 Console.WriteLine();

// A break to view the mapped columns - Enter to continue
 Console.ReadKey(); 

// show data in rows
  foreach (DataRow row in ds.Tables[ "mappedCliente"].Rows)

  {
  Console.WriteLine("IDCliente = {0}, Apelido = {1}, PrimNome = {2}",
      row["mappedIDCliente"], row["mappedApelido"],row["mappedPrimNome"]);

  }

  Console.WriteLine("\nEnd DataTableMapping - Press any Key to           continue");
  Console.ReadKey();　

}