DataView Object

DataView Object

The DataView object is more than a replacement for the DataTable’s Select method . Not only

are the results of the Select method on a DataTable not directly data bindable, but it is also not

a very efficient method to query rows.

Creating a DataView

A DataView can be created using any of the three constructor overloads it supports. The first constructor

overload allows you to create a DataView but not specify any information

DataView  dv = new DataView() ;

The second constructor directly ties the DataView to a DataTable

DataView dv = new DataView(TableName) ;

The third and final constructor of DataViews allows you to specify all that information in

one line of code.

DataView dv =new DataView(

EmpTable, "EmpID = 1001", "EmpName", DataViewRowState.Unchanged);

private void DataViewexample()
{
    // Create one DataTable with one column.
    DataTable tb = new DataTable("student");
    DataColumn dc = new DataColumn("stuentname",
        Type.GetType("System.String"));
    table.Columns.Add(colItem);

    // Add five items.
    DataRow NewRow;
    for(int i = 0; i <5; i++)
    {
        NewRow = table.NewRow();
        NewRow["studentname"] = "studentname " + i;
        table.Rows.Add(NewRow);
    }
    // Change the values in the table.
    table.Rows[0]["studentname"]="Ashish";
    table.Rows[1]["studentname"] = "Aditya";
    tb.AcceptChanges();

    // Create two DataView objects with the same table.
    DataView firstView = new DataView(table);
    DataView secondView = new DataView(table);

    // Print current table values.
    PrintTableOrView(table,"Current Values in Table");

    // Set first DataView to show only modified 
    // versions of original rows.
    firstView.RowStateFilter=DataViewRowState.ModifiedOriginal;

    // Print values.   
    PrinSTDtTableOrView(firstView,"First DataView: ModifiedOriginal");

    // Add one New row to the second view.
    DataRowView rowView;
    rowView=secondView.AddNew();
    rowView["studentname"] = "Anil";

    // Set second DataView to show modified versions of 
    // current rows, or New rows.
    secondView.RowStateFilter=DataViewRowState.ModifiedCurrent 
        | DataViewRowState.Added;
    // Print modified and Added rows.
    PrintTableOrView(secondView, 
        "Second DataView: ModifiedCurrent | Added");
}

private void PrintSTDTableOrView(DataTable table, string s)
{
    // This function prints values in the table or DataView.
    Console.WriteLine("\n" + s);
    for(int i = 0; i<table.Rows.Count;i++)
    {
        Console.WriteLine("\table" + table.Rows[i]["studentname"]);
    }
    Console.WriteLine();
}

private void PrintSTDTableOrView(DataView view, string label)
{

    // This overload prints values in the table or DataView.
    Console.WriteLine("\n" + s);
    for(int i = 0; i<view.Count;i++)
    {
        Console.WriteLine("\table" + view[i][""studentname"]);
    }
    Console.WriteLine();
}