Copying Rows from One DataTable to Another

Problem

You have records in a DataTable that you need to copy to another DataTable .

Solution

Use the ImportRow( ) method of the DataTable to copy DataRow objects from one DataTable to another. Three techniques for selecting records to copy are demonstrated in the following example:

• Use the Rows property to access rows in the DataRowCollection of the DataTable using the row index.
• Use the Select( ) method of the DataTable .
• Use the RowFilter property of a DataView for the DataTable .

The sample code creates a source DataTable containing the Orders table from Northwind. A second empty target DataTable is created with the same schema. One of the three techniques, as specified by the user , is used to copy records from the source table to the target table.

The C# code is shown in Example 5-1.

Example 5-1. File: CopyRowsBetweenTablesForm.cs

// Namespaces, variables, and constants using System; using System.Configuration; using System.Data; using System.Data.SqlClient; // Table name constants private const String ORDERS_TABLE = "Orders"; // Field name constants private const String ORDERID_FIELD = "OrderID"; // . . . // Fill the source table with schema and data. SqlDataAdapter da = new SqlDataAdapter("SELECT * FROM Orders", ConfigurationSettings.AppSettings["Sql_ConnectString"]); DataTable dt = new DataTable(ORDERS_TABLE); da.FillSchema(dt, SchemaType.Source); da.Fill(dt); // Clone the schema to the copy table. DataTable dtCopy = dt.Clone( ); if(rowRadioButton.Checked) { // Use ImportRow method to import the first three rows. for (int i = 0; i < 3; i++) { dtCopy.ImportRow(dt.Rows[i]); } } else if (selectRadioButton.Checked) { // Copy using result of Select( ) method. foreach(DataRow row in dt.Select(ORDERID_FIELD + " <= 10300")) { dtCopy.ImportRow(row); } } else if (filteredDataViewRadioButton.Checked) { // Copy using result of filtered DataView. DataView categoryView = dt.DefaultView; categoryView.RowFilter = ORDERID_FIELD + " >= 10300 AND " + ORDERID_FIELD + " < 10400"; for (int i = 0; i < categoryView.Count; i++) { dtCopy.ImportRow(categoryView[i].Row); } } // Bind the default view of the copy table to the grid. dataGrid.DataSource = dtCopy.DefaultView;

Discussion

Rows can be copied between tables using the ImportRow( ) methods of the DataTable object. The ImportRow( ) method requires that both the source and destination table have the same structure. In this example, the Clone( ) method of the DataTable creates a table with identical structure, but any technique that creates a table with an identical structure can be used.

Additionally, the Copy( ) method of the DataTable object can create a new DataTable having the same structure and data as the original as shown in the following code sample:

// Create the source table. DataTable dtSource = new DataTable("Source"); // . . . Fill the source table with data. // Create the destination table and copy the source table. DataTable dtDest = new DataTable("Dest"); dtDest = dtSource.Copy( );