Open(IDataReader) Method

On this page

Fetches data and sets the Active property to true.

Syntax

Visual Basic
C#


'Declaration Protected Overloads Overridable Sub Open( _ ByVal reader As IDataReader _ )


protected virtual void Open( IDataReader reader )

Parameters

reader

Remarks

The Open method executes the SelectCommand, creates columns and fills rows with data. Depending on values of miscellaneous properties, DbDataTable fetches either all data or some subset. For example, when DbDataTable is connected to a grid, it requests only data required for rendering (FetchAll=false mode), or the whole recordset (FetchAll=true mode).

For more information about DbDataTable fill capabilities please refer to descriptions of the following properties: FetchAll, MaxRecords, NonBlocking, QueryRecordCount, ReturnProviderSpecificTypes, StartRecord. The following methods also provide additional features: BeginFill, FillPage, FillSchema.

Example

The following example demonstrates how to use the Open() method.

csharp


static void UseDataTable(DbDataTable myDataTable, DbCommand myCommand) { myCommand.CommandText = "SELECT * FROM Dept"; myDataTable.SelectCommand = myCommand; try { myDataTable.FetchAll=true; myDataTable.Open(); foreach(DataRow myRow in myDataTable.Rows) { foreach(DataColumn myCol in myDataTable.Columns) { Console.Write(myRow[myCol]+"\t"); } Console.WriteLine(); } } finally { myDataTable.Close(); } }

static void UseDataTable(DbDataTable myDataTable, DbCommand myCommand)
{
  myCommand.CommandText = "SELECT * FROM Dept";
  myDataTable.SelectCommand = myCommand;
  try
  {
        myDataTable.FetchAll=true;
    myDataTable.Open();
    foreach(DataRow myRow in myDataTable.Rows)
    {
      foreach(DataColumn myCol in myDataTable.Columns)
      {
        Console.Write(myRow[myCol]+"\t");
      }
      Console.WriteLine();
    }
  }
  finally
  {
    myDataTable.Close();
  }
}

Visual Basic


Public Sub UseDataTable(ByVal myDataTable As DbDataTable, ByVal myCommand As DbCommand) myCommand.CommandText = "SELECT * FROM Dept" myDataTable.SelectCommand = myCommand Try myDataTable.FetchAll=True myDataTable.Open() Dim myRow As DataRow Dim myCol As DataColumn For Each myRow In myDataTable.Rows For Each myCol In myDataTable.Columns Console.Write(myRow(myCol) & Chr(9)) Next myCol Console.WriteLine() Next myRow Finally myDataTable.Close() End Try End Sub

Public Sub UseDataTable(ByVal myDataTable As DbDataTable, ByVal myCommand As DbCommand)
  myCommand.CommandText = "SELECT * FROM Dept"
  myDataTable.SelectCommand = myCommand
  Try
        myDataTable.FetchAll=True
    myDataTable.Open()
    Dim myRow As DataRow
    Dim myCol As DataColumn
    For Each myRow In myDataTable.Rows
      For Each myCol In myDataTable.Columns
        Console.Write(myRow(myCol) & Chr(9))
      Next myCol
      Console.WriteLine()
    Next myRow
  Finally
    myDataTable.Close()
  End Try
End Sub

Reference

DbDataTable Class
DbDataTable Members
Overload List
Active Property
Fill Method

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