7.6 Loading Data

There are three methods that can add new rows to the DataTable. The NewRow( ) method creates a new empty DataRow with the same schema as the DataTable. After creating the row, it can be added to the DataTable using the Add( ) method of the DataRowCollection:

// create the target table
DataTable dt = new DataTable("MyTable");
dt.Columns.Add("Column1", typeof(System.Int32));
dt.Columns.Add("Column2", typeof(System.String));

// create and add a new row to the table
DataRow newrow = dt.NewRow();
newrow["Column1"] = 1;
newrow["Column2"] = "Row 1";
dt.Rows.Add(newrow);

The LoadDataRow( ) method takes an array of values and attempts to find a row with a matching primary key. If the primary key is found, the values replace the existing data for the row; otherwise a new row is added. The LoadDataRow( ) method takes a Boolean AcceptChanges argument. If the AcceptChanges value is true, AcceptChanges is called to accept all changes for both inserted and modified rows. If AcceptChanges is false, the DataRowState fields of newly added rows are marked as insertions, while changes to existing rows are marked as modifications.

The BeginLoadData( ) method turns off all constraints, notifications, and index maintenance for the DataTable while data is loaded; the EndLoadData( ) method turns them back on. Calling BeginLoadData( ) and EndLoadData( ) methods might result in performance improvements when adding a series of DataRows to the DataTable using the LoadDataRow( ) method. If there are constraint violations when the EndLoadData( ) method is called, a ConstraintException is raised. The following example illustrates these methods:

// create the target table
DataTable dt = new DataTable("MyTable");
dt.Columns.Add("Column1", typeof(System.Int32));
dt.Columns.Add("Column2", typeof(System.String));

// add two rows to the DataTable dt
dt.BeginLoadData();
dt.LoadDataRow(new Object[]{1,"Row 1"}, false);
dt.LoadDataRow(new Object[]{2,"Row 2"}, false);
dt.EndLoadData();

Finally, the ImportRow( ) method accepts a DataRow object argument and either adds the row to the table or updates an existing row with a matching primary key in the table, using the existing schema and preserving the existing DataRowState of the row:

// create the target table
DataTable dt = new DataTable("MyTable");
dt.Columns.Add("Column1", typeof(System.Int32));
dt.Columns.Add("Column2", typeof(System.String));

DataRow newrow = dt.NewRow();
newrow["Column1"] = 1;
newrow["Column2"] = "Row 1";
dt.Rows.ImportRow(newrow);