VB.Net/Data Structure/Connection

Материал из VB Эксперт
Перейти к: навигация, поиск

Check the state of the connection and report appropriately

<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 FirstName, LastName 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()
           "Check the state of the connection and report appropriately
           If objConnection.State = ConnectionState.Open Then
               Console.WriteLine( "Database connection is open")
           Else
               Console.WriteLine("Database connection failed")
           End If
       Catch OleDbExceptionErr As OleDbException
           "Write the exception
           Console.WriteLine(OleDbExceptionErr.Message)
       Catch InvalidOperationExceptionErr As InvalidOperationException
           "Write the exception
           Console.WriteLine(InvalidOperationExceptionErr.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>


Database Connection Properties: version, data source, WorkstationId, database and etc

<source lang="vbnet"> Imports System Imports System.Data Imports System.Data.SqlClient public class MainClass

  Shared Sub Main()
     Dim connString As String = "server=(local)\SQLEXPRESS; " & _
        "integrated security=sspi;"
     Dim conn As New SqlConnection(connString)
     Try
        conn.Open()
        Console.WriteLine("Connection Opened")
        Console.WriteLine("Connection Properties")
        Console.WriteLine("- ConnectionString : {0}",conn.ConnectionString)
        Console.WriteLine("- Database : {0}",conn.Database)
        Console.WriteLine("- DataSource : {0}", conn.DataSource)
        Console.WriteLine("- ServerVersion : {0}", conn.ServerVersion)
        Console.WriteLine("- State : {0}", conn.State)
        Console.WriteLine("- WorkstationId : {0}", conn.WorkstationId)
     Catch ex As SqlException
        Console.WriteLine("Error: " & ex.ToString())
     Finally
        conn.Close()
        Console.WriteLine("Connection Closed")
     End Try
  End Sub

End Class

      </source>