The SqlConnection Object is Handling the part of physical communication between the application and the SQL Server Database. An instance of the SqlConnection class in .NET Framework is supported the Data Provider for SQL Server Database. The SqlConnection instance takes Connection String as argument and pass the value to the Constructor statement. When the connection is established , SQL Commands may be executed, with the help of the Connection Object, to retrieve or manipulate data in the database. Once the Database activities over , Connection should be closed and release the database resources .

The Close() method in SqlConnection class is used to close the Database Connection. The Close method rolls back any pending transactions and releases the Connection from the SQL Server Database.

Imports System.Data.SqlClient
Public Class Form1
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim connetionString As String
        Dim cnn As SqlConnection
        connetionString = "Data Source=ServerName;Initial Catalog=DatabaseName;User ID=UserName;Password=Password"
        cnn = New SqlConnection(connetionString)
        Try
            cnn.Open()
            MsgBox("Connection Open ! ")
            cnn.Close()
        Catch ex As Exception
            MsgBox("Can not open connection ! ")
        End Try
    End Sub
End Class