关于对DataTable进行操作的几个例子总结

第一个，这个主要是在一个表里选择一些行。但是，如果选择的依据是行的值为空白，也就是没有值的话，我不知条件怎么写，试了好多种方法，不行，所以最后也没用这个。这个方法的条件好像是模仿SQL里面的写法。

private void GetRowsByFilter()
{
    DataTable table = DataSet1.Tables["Orders"];
    // Presuming the DataTable has a column named Date.
    string expression;
    expression = "Date > '1/1/00'";
    DataRow[] foundRows;

    // Use the Select method to find all rows matching the filter.
    foundRows = table.Select(expression);

    // Print column 0 of each returned row.
    for(int i = 0; i < foundRows.Length; i ++)
    {
        Console.WriteLine(foundRows[i][0]);
    }
}

第二个，主要是用DataRow 的delete方法删除掉某些行，可以和第三个例子做一下对比

private void DemonstrateDeleteRow()
{
    // Create a simple DataTable with two columns and ten rows.
    DataTable table = new DataTable("table");
    DataColumn idColumn = new DataColumn("id",
        Type.GetType("System.Int32"));
    idColumn.AutoIncrement=true;
    DataColumn itemColumn = new DataColumn("item", 
        Type.GetType("System.String"));
    table.Columns.Add(idColumn);
    table.Columns.Add(itemColumn);

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

    DataRowCollection itemColumns = table.Rows;
    itemColumns[2].Delete();
    itemColumns[5].Delete();
    Console.WriteLine(itemColumns[3].RowState.ToString());

    // Reject changes on one deletion.
    itemColumns[3].RejectChanges();

    // Change the value of the column so it stands out.
    itemColumns[3]["item"] = "Deleted, Undeleted, Edited";

    // Accept changes on others.
    table.AcceptChanges();
}

第三个，vb写的例子，我也懒得改了。应用行集合的remove方法删除行。

Private Sub RemoveFoundRow(ByVal table As DataTable)
    Dim rowCollection As DataRowCollection = table.Rows

    ' Test to see if the collection contains the value.
    If rowCollection.Contains(TextBox1.Text) Then
        Dim foundRow As DataRow = rowCollection.Find(TextBox1.Text)
        rowCollection.Remove(foundRow)
        Console.WriteLine("Row Deleted")
    Else
        Console.WriteLine("No such row found.")
    End If
 End Sub