Updating with ADO.NET

[Radovan Radic]

Hello,

I want to use readonly DataGrid to show the data, and when user wants to
insert/update/delete records i bring the form for the user input and then
update DataGrid and DataBase contents.
If i Call
((DataSet)DataGrid1.DataSource).Tables["MyTableName"].Rows[selectedRow]["col
umn"] = someValue and call
dataAdapter.Update((DataSet)DataGrid1.DataSource," MyTableName").
i wont be able to update DataSet that is a result of JOIN select command,
right?
Is this command
((DataSet)DataGrid1.DataSource).Tables["MyTableName"].Rows[selectedRow]["col
umn"] = someValue
gonna update DataGrid1 contents, or i have to update DataGrid cells
manually?
Then i could use
// build cmdStr command, for update/insert/delete
SqlCommand cmd = new SqlCommand(cmdStr,connection);
cmd.ExecuteNonQuery();

Is this a good practice? (sorry if i wasnt clear enough)

Another question about databases:
If i understood properly, MSDE edition of SQL Server is free to use for
developping purposes. Is it free for commercial use, and if yes, how many
connections can i have at the same time, i need < 10 connections.

Thanks,
Radovan