ExecuteScalar
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim orden As New OleDbCommand
Dim coneccion As New OleDbConnection(“Provider=Microsoft.Jet.OLEDB.4.0; Data Source=Database2.mbd”)
Dim q As String = “SELECT existencias FROM producto WHERE codigo = ” & TextBox1.Text
Dim stock As Integer
orden = New OleDbCommand(q, coneccion)
orden.Connection.Open()
stock = orden.ExecuteScalar()
orden.Connection.Close()
If stock – Val(TextBox2.Text) < 0 Then
MessageBox.Show(“Stock insuficiente”)
Else
Dim stock2 As Integer = stock – Val(TextBox2.Text)
q = “UODATE producto SET stock = ” + stock2 + ” WHERE codigo = @codigo”
orden.Parameters.Add(New OleDbParameter(“@codigo”, OleDbType.Integer))
orden.Parameters(“@codigo”).Value = TextBox2.Text
orden = New OleDbCommand(q, coneccion)
orden.Connection.Open()
orden.ExecuteNonQuery()
orden.Connection.Close()
End If
End Sub
