You don't need to call UpdatePanel1.Update()
in your Button1_Click method since Button1 is a trigger for your UpdatePanel. Instead you must call GridView1.DataBind() to refetch data from DB, like this :
Protected Sub Button1_Click(ByVal sender As Object, ByVal e As EventArgs) Handles Button3.Click
Dim connStr As String = "connection string works"
Dim cmdStr As String = "INSERT INTO [test] ([datetime],[col1],[col2],[col3]) VALUES (@datetime,@col1,@col2,@col3);"
Try
Using conn As New SqlConnection(connStr)
Using cmd As New SqlCommand(cmdStr, conn)
conn.Open()
cmd.Parameters.AddWithValue("@datetime", DateTime.Now)
cmd.Parameters.AddWithValue("@col1", TextBox1.Text)
cmd.Parameters.AddWithValue("@col2", TextBox2.Text)
cmd.Parameters.AddWithValue("@col3", TextBox3.Text)
cmd.ExecuteNonQuery()
conn.Close()
cmd.Dispose()
conn.Dispose()
End Using
End Using
Catch ex As Exception
End Try
GridView1.Databind()
End Sub