VB.Net/Database ADO.net/OleDbDataReader
Use OleDbDataReader to read data
<source lang="vbnet"> 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
</source>
<A href="http://www.vbex.ru/Code/VBDownload/Employee.zip">Employee.zip( 7 k)</a>
Use OleDbDataReader to read data from "select" command
<source lang="vbnet"> 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
</source>
<A href="http://www.vbex.ru/Code/VBDownload/Employee.zip">Employee.zip( 7 k)</a>