hello,

i want to update a field ("ConvB") in a table MamConv.

first i do this ; MamConvEntity conv = new MamConvEntity((string)Session["idconv"]);

now i need to cast this string "conv1.ConvBesoin" in a type of MamConvEntity field to do that ;

(cast??) conv1.ConvBesoin = tbx_ConvB.Text;

and after save();

Is it possible ?

You shouldn't need to do any casting if the field type in your database is a string.

MamConvEntity conv1 = new MamConvEntity((string)Session["idconv"]);
conv1.ConvBesoin = tbx_ConvB.Text;
conv1.Save();