Row States and Row Versions 

ADO.NET manages rows in tables using row states and versions. A row state indicates the status of a row; row versions maintain the values stored in a row as it is modified, including current, original, and default values. For example, after you have made a modification to a column in a row, the row will have a row state of Modified, and two row versions: Current, which contains the current row values, and Original, which contains the row values before the column was modified.

Each DataRow object has a RowState property that you can examine to determine the current state of the row. The following table gives a brief description of each RowState enumeration value.

When AcceptChanges is called on a DataSet, DataTable, or DataRow, all rows with a row state of Deleted are removed. The remaining rows are given a row state of Unchanged, and the values in the Original row version are overwritten with the Current row version values. When RejectChanges is called, all rows with a row state of Added are removed. The remaining rows are given a row state of Unchanged, and the values in the Current row version are overwritten with the Original row version values.

You can view the different row versions of a row by passing a DataRowVersion parameter with the column reference, as shown in the following example.

Dim custRow As DataRow = custTable.Rows(0)
Dim custID As String = custRow("CustomerID", DataRowVersion.Original).ToString()

DataRow custRow = custTable.Rows[0];
string custID = custRow["CustomerID", DataRowVersion.Original].ToString();

The following table gives a brief description of each DataRowVersion enumeration value.

You can test whether a DataRow has a particular row version by calling the HasVersion method and passing a DataRowVersion as an argument. For example, DataRow.HasVersion(DataRowVersion.Original) will return false for newly added rows before AcceptChanges has been called.

The following code example displays the values in all the deleted rows of a table. Deleted rows do not have a Current row version, so you must pass DataRowVersion.Original when accessing the column values.

Dim catTable As DataTable = catDS.Tables("Categories")

Dim delRows() As DataRow = catTable.Select(Nothing, Nothing, DataViewRowState.Deleted)

Console.WriteLine("Deleted rows:" & vbCrLf)

Dim catCol As DataColumn
Dim delRow As DataRow

For Each catCol In catTable.Columns
  Console.Write(catCol.ColumnName & vbTab)
Next
Console.WriteLine()

For Each delRow In delRows
  For Each catCol In catTable.Columns
    Console.Write(delRow(catCol, DataRowVersion.Original) & vbTab)
  Next
  Console.WriteLine()
Next

DataTable catTable = catDS.Tables["Categories"];

DataRow[] delRows = catTable.Select(null, null, DataViewRowState.Deleted);

Console.WriteLine("Deleted rows:\n");

foreach (DataColumn catCol in catTable.Columns)
  Console.Write(catCol.ColumnName + "\t");
Console.WriteLine();

foreach (DataRow delRow in delRows)
{
  foreach (DataColumn catCol in catTable.Columns)
    Console.Write(delRow[catCol, DataRowVersion.Original] + "\t");
  Console.WriteLine();
}

See Also

Reference

DataRowCollection Class
DataRow.RowState Property
DataRowVersion Enumeration
DataViewRowState Enumeration

Other Resources

Manipulating Data in a DataTable