After the VB.net program is closed, the background is still connected to SQL

This section writes Excel data into the database in batches, but how can the program still run in the background after closing the program?Is the connection not closed?

 For ii = 0 To ListBox1.Items.Count - 1 fileName = ListBox1.Items.Item(ii) Dim ExcelConnection As New System.Data.OleDb.OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0; Data Source='" & fileName & "'; Extended Properties=""Excel 12.0Xml; HDR=Yes""") ExcelConnection.Open() Dim expr As String = "SELECT [PASS_ID] FROM [split details$]" Dim objCmdSelect As OleDbCommand = New OleDbCommand(expr, ExcelConnection) Dim objDR As OleDbDataReader Dim SQLconn As New SqlConnection() Dim ConnString As String = "server=localhost;database=STdata;user id=sa;password=Nngs8888!" SQLconn.ConnectionString = ConnString SQLconn.Open() Using bulkCopy As New SqlBulkCopy(SQLconn) bulkCopy.DestinationTableName = "chaifen"Try objDR = objCmdSelect.ExecuteReader bulkCopy.WriteToServer(objDR) SQLconn.Close() Catch ex As Exception MsgBox(ex.ToString) End Try End Using ExcelConnection.Close() ProgressBar1.Value = ii Next