Add column to SQL table and populate to datagridview - sql

Question

I have a windows form application with databound datagridview. I want to add column at run time (if user wants to add more column to it). So on button click I wanted to add column. I have added following code to event it adds column in server explorer view under tables column's list but does not show in table definition neither in data source window (in column list under table) nor in datagridview.
Imports System.Configuration
Imports System.Data.SqlClient
Public Class Form3
Private Sub Form3_Load(sender As Object, e As EventArgs) Handles MyBase.Load
'TODO: This line of code loads data into the 'Small_databaseDataSet.newtable' table. You can move, or remove it, as needed.
Me.NewtableTableAdapter.Fill(Me.Small_databaseDataSet.newtable)
End Sub
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
AddColumn()
End Sub
Private Sub AddColumn()
Dim connString As String = "Data Source=(localDb)\ProjectsV13;Initial Catalog=small database;Integrated Security=True"
Dim dt As New DataTable
Using conn As New SqlConnection(connString)
Dim str As String = "ALTER TABLE newtable ADD " & TextBoxX1.Text & " INT null;"
Using comm As New SqlCommand(str, conn)
conn.Open()
comm.ExecuteNonQuery()
End Using
End Using
Validate()
DataGridViewX1.Columns.Clear()
NewtableTableAdapter.Update(Small_databaseDataSet.newtable)
NewtableTableAdapter.Fill(Small_databaseDataSet.newtable)
DataGridViewX1.DataSource = NewtableBindingSource
End Sub
End Class

Answer 1

Change this line of code:
' Add the keyword NULL and brackets around the column name
Dim comm As New SqlCommand("ALTER TABLE testTable ADD [col1] INT NULL", conn)
If I wanted to have the new column to show up automatically, I would re-query the database, retrieving the data on that table and just set the datagridview datasource to the resultset like:
'I assume the datagridview name is DataGridView1
DataGridView1.Columns.Clear()
DataGridView1.DataSource = USTDatabaseDataSet
DataGridView1.DataMember = "testTable"
DataGridView1.DataBind()

Answer 2

A DataReader is used to retrieve data. Since there is no data retrieved nothing is loaded into your DataTable except maybe a return value of success or failure. The Using statements ensure that your objects are closed and disposed properly even if there is an error.
Private Sub AddColumn()
Dim connString As String = ConfigurationManager.ConnectionStrings("USTDatabaseConnectionString").ConnectionString
Dim dt As New DataTable
Using conn As New SqlConnection(connString)
Using comm As New SqlCommand("ALTER TABLE testTable ADD col1 INT;", conn)
conn.Open()
comm.ExecuteNonQuery()
End Using
Using com2 As New SqlCommand("Select * From testTable;", conn)
Using reader As SqlDataReader = com2.ExecuteReader
dt.Load(reader)
conn.Close()
End Using
End Using
End Using
DataGridView1.DataSource = dt
End Sub