VISUAL BASIC .Net

CONECTAR A SQL SERVER CON ADO.NET

Este ejemplo crea un formulario llamado Conexión para conectarse a una base de datos de SQL Server llamada Northwind, usando autenticación de windows, la progra del formulario se detalla a continuación.   Imports System.Data Imports System.Data.SqlClient Public Class Conexion     Dim WithEvents Cn As New SqlConnection     Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click         Try             Cn.ConnectionString = "data source=VISOAL76;initial catalog=Northwind;integrated security=true"             Cn.Open()         Catch XcpSQL As SqlException             MessageBox.Show(XcpSQL.Number)         Catch Xcp As Exception             MessageBox.Show("Se ha producido un error")         End Try     End Sub     Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click         Cn.Close()         Cn.Dispose()     End Sub     Private Sub Cn_StateChange(ByVal sender As Object, ByVal e As System.Data.StateChangeEventArgs) Handles Cn.StateChange         MessageBox.Show("Estado Actual:" & e.CurrentState.ToString)     End Sub     Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click         Dim cm As New SqlCommand("Select companyname from customers", Cn)         Dim rds As SqlDataReader = cm.ExecuteReader         ListBox1.Items.Clear()         Do While rds.Read             ListBox1.Items.Add(rds.GetString(0))         Loop         rds.Close()     End Sub     Private Sub Conexion_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load     End Sub End Class