VB.Net/Database ADO.net/OleDbDataReader

Use OleDbDataReader to read data

Imports System
Imports System.Data
Imports System.Data.OleDb
Imports System.Data.SqlClient
Imports System.Collections
Imports System.Windows.Forms
Imports System.Resources
Public Class MainClass
    Shared Sub Main()
        "Declare variables and objects
        Dim strConnectionString As String = _
            "Provider=Microsoft.Jet.OLEDB.4.0;" & _
            "Data Source=Employee.mdb;"
        Dim objConnection As New OleDbConnection(strConnectionString)
        Dim strSQL As String = "SELECT * FROM Employee"
        Dim objCommand As New OleDbCommand(strSQL, objConnection)
        Dim objDataAdapter As New OleDbDataAdapter(objCommand)
        Dim objDataTable As New Data.DataTable("Employee")
        Dim objDataRow As DataRow
        Try
            "Open the database connection
            objConnection.Open()
        Catch OleDbExceptionErr As OleDbException
            "Write the exception
            Console.WriteLine(OleDbExceptionErr.Message)
        Catch InvalidOperationExceptionErr As InvalidOperationException
            "Write the exception
            Console.WriteLine(InvalidOperationExceptionErr.Message)
        End Try

        "Declare an OleDbDataReader object
        Dim objDataReader As OleDbDataReader
        Try
            "Execute the SQL text
            objDataReader = objCommand.ExecuteReader()
            "Check to see if we have data
            If objDataReader.HasRows Then
                "Process all rows
                While objDataReader.Read()
                    "Get the data in each column
                    For intIndex As Integer = 0 To objDataReader.FieldCount - 1
                        Console.WriteLine( objDataReader.Item(intIndex).ToString & ", ")
                    Next
                End While
            End If
            "Close the reader
            objDataReader.Close()
        Catch OleDbExceptionErr As OleDbException
            Console.WriteLine(OleDbExceptionErr.Message)
        End Try


        "Close the database connection
        objConnection.Close()
        "Clean up
        objDataRow = Nothing
        objDataTable.Dispose()
        objDataTable = Nothing
        objDataAdapter.Dispose()
        objDataAdapter = Nothing
        objCommand.Dispose()
        objCommand = Nothing
        objConnection.Dispose()
        objConnection = Nothing
    End Sub
End Class

<A href="http://www.vbex.ru/Code/VBDownload/Employee.zip">Employee.zip( 7 k)</a>

Use OleDbDataReader to read data from "select" command

Imports System
Imports System.Data
Imports System.Data.OleDb
public class MainClass
   Shared Sub Main()
      "Create Connection object
      Dim thisConnection As New OleDbConnection _
         ("Provider=Microsoft.Jet.OLEDB.4.0;" & _
          "Data Source=Employee.mdb")
      "Create Command object
      Dim thisCommand As New OleDbCommand _
         ("SELECT ID, FirstName FROM Employee", _
          thisConnection)
      Try
         " Open Connection
         thisConnection.Open()
         Console.WriteLine("Connection Opened")
         " Execute Query
         Dim thisReader As OleDbDataReader = thisCommand.ExecuteReader()
         While (thisReader.Read())
            Console.WriteLine("FirstName: {0} {1}", _
               thisReader.GetValue(0), thisReader.GetValue(1))
         End While
      Catch ex As OleDbException
         " Display error
         Console.WriteLine("Error: " & ex.ToString())
      Finally
         " Close Connection
         thisConnection.Close()
         Console.WriteLine("Connection Closed")
      End Try   
   End Sub
End Class

<A href="http://www.vbex.ru/Code/VBDownload/Employee.zip">Employee.zip( 7 k)</a>