经典操作之DataSet&DataTable

private void DemonstrateMergeMissingSchema()
  {
   // Create a DataSet with one table, two columns,
   // and three rows.
   DataSet dataSet = new DataSet("dataSet");
   DataTable table = new DataTable("Items");
   DataColumn idColumn = new DataColumn("id",
    Type.GetType("System.Int32"));
   idColumn.AutoIncrement=true;
   DataColumn itemColumn = new DataColumn("Item",
    Type.GetType("System.Int32"));
   // DataColumn array to set primary key.

   DataColumn[] keyColumn= new DataColumn[1];
   DataRow row;
   // Create variable for temporary DataSet.
   DataSet changeDataSet;

   // Add RowChanged event handler for the table.
   table.RowChanged+= new DataRowChangeEventHandler(
    Row_Changed);
   dataSet.Tables.Add(table);
   table.Columns.Add(idColumn);
   table.Columns.Add(itemColumn);

   // Set primary key column.
   keyColumn[0]= idColumn;
   table.PrimaryKey=keyColumn;

   // Add ten rows.
   for(int i = 0; i <10;i++)
   {
    row=table.NewRow();
    row["Item"]= i;
    table.Rows.Add(row);
   }

   // Accept changes.
   dataSet.AcceptChanges();
   DataGrid2.DataSource=dataSet;
   DataGrid2.DataBind();
   //PrintValues(dataSet, "Original values");

   // Change row values.
   table.Rows[0]["Item"]= 50;
   table.Rows[1]["Item"]= 111;

   // Add one row.
   row=table.NewRow();
   row["Item"]=74;
   table.Rows.Add(row);

   // Insert code for error checking. Set one row in error.
   table.Rows[1].RowError= "over 100";
   //PrintValues(dataSet, "Modified and New Values");
   // If the table has changes or errors, create a subset DataSet.
   if(dataSet.HasChanges(DataRowState.Modified |
    DataRowState.Added)& dataSet.HasErrors)
   {
    // Use GetChanges to extract subset.
    changeDataSet = dataSet.GetChanges(
     DataRowState.Modified|DataRowState.Added);
    //PrintValues(changeDataSet, "Subset values");

    // Insert code to reconcile errors. Reject the changes.
    foreach(DataTable changeTable in changeDataSet.Tables)
    {
     if (changeTable.HasErrors)
     {
      foreach(DataRow changeRow in changeTable.Rows)
      {
       //Console.WriteLine(changeRow["Item"]);
       if((int)changeRow["Item",
        DataRowVersion.Current ]> 100)
       {
        changeRow.RejectChanges();
        changeRow.ClearErrors();
       }
      }
     }
    }
    // Add a column to the changeDataSet to change the schema.
    changeDataSet.Tables["Items"].Columns.Add(
     new DataColumn("newColumn"));
    //PrintValues(changeDataSet, "Reconciled subset values");

    // Add values to the rows for each column.
    foreach(DataRow rowItem in changeDataSet.Tables["Items"].Rows)
    {
     rowItem["newColumn"] = "my new schema value";
    }
    DataGrid2.DataSource=dataSet;
    DataGrid2.DataBind();
    DataGrid3.DataSource=changeDataSet;
    DataGrid3.DataBind();
    // Merge changes back to first DataSet.
    dataSet.Merge(changeDataSet, false,
    System.Data.MissingSchemaAction.Add);
   }
   //PrintValues(dataSet, "Merged Values");
   DataGrid1.DataSource=dataSet;
   DataGrid1.DataBind();
  }
 
  private void Row_Changed(object sender, DataRowChangeEventArgs e)
  {
   Console.WriteLine("Row Changed " + e.Action.ToString()
    + "\table" + e.Row.ItemArray[0]);
  }
 
  private void PrintValues(DataSet dataSet, string label)
  {
   Console.WriteLine("\n" + label);
   foreach(DataTable table in dataSet.Tables)
   {
    Console.WriteLine("TableName: " + table.TableName);
    foreach(DataRow row in table.Rows)
    {
     foreach(DataColumn column in table.Columns)
     {
      Console.Write("\table " + row[column] );
     }
     Console.WriteLine();
    }
   }
  }

id         Item
0         50
1         111
2         2
3         3
4         4
5         5
6         6
7         7
8         8
9         9
10        74


id         Item         newColumn
0         50             my new schema value
1         1               my new schema value
10         74             my new schema value

 id         Item         newColumn
0           50            my new schema value
1            1             my new schema value
2             2  
3             3  
4             4  
5             5  
6             6  
7             7  
8             8  
9             9  
10         74         my new schema value