Access database too slow populating DatagridView - vb.net

Question

I have an app with several datagridviews, and now, with more than 260 rows, my datagrid is too slow filling up, I don't know how I can lower the time.
Here is my codes:
Public cs As String = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" & Application.StartupPath & "\BD_Estaleiro.accdb"
Public con As New OleDbConnection(cs)
Public cmd As OleDbCommand
Public dr As OleDbDataReader
Public query As String
Reader Function:
Public Function executar_query_Reader(ByVal Instrucao As String) As OleDb.OleDbDataReader
Dim datareader As OleDbDataReader = Nothing
cmd = New OleDbCommand(Instrucao, con)
Try
If con.State = ConnectionState.Open Then
con.Close()
End If
con.Open()
datareader = cmd.ExecuteReader
Catch ex As Exception
MessageBox.Show(ex.Message) 'mensagem de erro, se aplicavel
Finally
End Try
Return datareader 'retornar os dados atraves da variavel datareader
End Function
Populating the Datagrid:
Public Sub carregar_saidas(ByVal DG As DataGridView)
n_rows = 0
DG.Rows.Clear()
query = "Select * from tbl_saidas as s, tbl_produtos as p Where s.Produto=p.Produto Order By s.Data DESC"
dr = executar_query_Reader(query)
While dr.Read
n_rows += 1
Dim n As Integer = DG.Rows.Add()
DG.Rows.Item(n).Cells(0).Value = dr("ID")
DG.Rows.Item(n).Cells(1).Value = dr("s.Produto")
DG.Rows.Item(n).Cells(2).Value = dr("s.Quantidade")
DG.Rows.Item(n).Cells(3).Value = dr("Unidade")
DG.Rows.Item(n).Cells(4).Value = dr("Obra")
DG.Rows.Item(n).Cells(5).Value = Format(dr("Data"), "dd/MM/yyyy")
DG.Rows.Item(n).Cells(6).Value = Format$(CSng(dr("Valor_uni")), "###,####,##0.00") & " €"
DG.Rows.Item(n).Cells(7).Value = Format$(CSng(dr("Total")), "###,####,##0.00") & " €"
End While
con.Close()
End Sub
Thanks for any help

Answer 1

Rather than adding individual Rows and Columns, you want to bind to the grid:
Public Sub carregar_saidas(ByVal DG As DataGridView)
Dim query As String = "Select * from tbl_saidas as s, tbl_produtos as p Where s.Produto=p.Produto Order By s.Data DESC"
Dim dr As OleDbDataReader = executar_query_Reader(query)
DG.DataSource = dr
End Sub
You'll need to have defined the columns on DataGridView to map the fields in the data reader.
You should also look into modifying the executar_query_Reader() method to support parameterized queries.