C# DataRow

　　DataRow 模拟的是数据库中的一行。使用 HasVersion 和 IsNull 属性确定特定行值的状态。

1. 添加行

　　创建新的 DataRow，要使用 DataTable 对象的 NewRow 方法。然后，使用 Add 方法将新的 DataRow 添加到 DataRowCollection 中。最后，调用 DataTable 对象的 AcceptChanges 方法以确认是否已添加。具体描述参考我另一篇文章 C# DataTable。

private void CreateNewDataRow()
{
    // Use the MakeTable function below to create a new table.
    DataTable table;
    table = MakeNamesTable();

    // Once a table has been created, use the 
    // NewRow to create a DataRow.
    DataRow row;
    row = table.NewRow();

    // Then add the new row to the collection.
    row["fName"] = "John";
    row["lName"] = "Smith";
    table.Rows.Add(row);

    foreach(DataColumn column in table.Columns)
        Console.WriteLine(column.ColumnName);
    dataGrid1.DataSource=table;
}

private DataTable MakeNamesTable()
{
    // Create a new DataTable titled 'Names.'
    DataTable namesTable = new DataTable("Names"); 

    // Add three column objects to the table.
    DataColumn idColumn = new  DataColumn();
    idColumn.DataType = System.Type.GetType("System.Int32");
    idColumn.ColumnName = "id";
    idColumn.AutoIncrement = true;
    namesTable.Columns.Add(idColumn);

    DataColumn fNameColumn = new DataColumn();
    fNameColumn.DataType = System.Type.GetType("System.String");
    fNameColumn.ColumnName = "Fname";
    fNameColumn.DefaultValue = "Fname";
    namesTable.Columns.Add(fNameColumn);

    DataColumn lNameColumn = new DataColumn();
    lNameColumn.DataType = System.Type.GetType("System.String");
    lNameColumn.ColumnName = "LName";
    namesTable.Columns.Add(lNameColumn);

    // Create an array for DataColumn objects.
    DataColumn [] keys = new DataColumn [1];
    keys[0] = idColumn;
    namesTable.PrimaryKey = keys;

    // Return the new DataTable.
    return namesTable;
}

///////////////////////////////////////////////////////
DataRow workRow;
for (int i = 0; i <= 9; i++) 
{
  workRow = workTable.NewRow();
  workRow[0] = i;
  workRow[1] = "CustName" + i.ToString();
  workTable.Rows.Add(workRow);
}

2. 删除行

　　您可通过调用 DataRowCollection 的 Remove 方法或调用 DataRow 对象的 Delete 方法，从 DataRowCollection 中删除 DataRow。Remove 方法将行从集合中移除。与此相反，Delete 标记要移除的 DataRow。在调用AcceptChanges 方法时发生实际移除。通过调用 Delete，您可在实际删除行之前以编程方式检查哪些行被标记为移除。具体描述参考我另外一篇文章 C# DataTable。

private void DemonstrateAcceptChanges()
{
    //Run a function to create a DataTable with one column.
    DataTable table = MakeTable();
    DataRow row;

    // Create a new DataRow.
    row = table.NewRow();
    // Detached row.
    Console.WriteLine("New Row " + row.RowState);

    table.Rows.Add(row);
    // New row.
    Console.WriteLine("AddRow " + row.RowState);

    table.AcceptChanges();
    // Unchanged row.
    Console.WriteLine("AcceptChanges " + row.RowState);

    row["FirstName"] = "Scott";
    // Modified row.
    Console.WriteLine("Modified " + row.RowState);

    row.Delete();
    // Deleted row.
    Console.WriteLine("Deleted " + row.RowState);
}

private DataTable MakeTable()
{
    // Make a simple table with one column.
    DataTable table = new DataTable("table");
    DataColumn fnameColumn = new DataColumn(
        "FirstName", Type.GetType("System.String"));
    table.Columns.Add(fnameColumn);
    return table;
}