C# delete from two tables

No, this is all for now ...

OracleConnection connG = conexiune.conn;
            try
            {
                foreach (ListViewItem itm in listView1.Items)
                {
                    string cod;
                    if (itm.Checked == true)
                    {
                        cod = itm.Text;
                        string delete_sql1 = "delete from furnizor f, comanda c where f.cod_furnizor = c.cod_furnizor and cod_furnizor = :cod_furnizor";
                        OracleCommand cmd = new OracleCommand(delete_sql1, connG);
                        cmd.Parameters.Add(new OracleParameter(":cod_furnizor", Convert.ToInt32(cod)));
                        cmd.ExecuteNonQuery();
                        cmd.Dispose();
                    }
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message.ToString());
            }

voloda2 is right: Use Begin Transaction so that it will rollback if anything fails.

Here is an example taken from http://download.oracle.com/docs/cd/B28928_01/doc/server.103/b28923/nvadonet.htm

OracleConnection conn = new OracleConnection ("DSN=consroot;uid=system");
conn.Open();
IDbTransaction trans = conn.BeginTransaction(); // Turn off AUTOCOMMIT
OracleCommand cmd = (OracleCommand)conn.CreateCommand();
cmd.CommandText = "create table TEST1 (c0 number)";
cmd.ExecuteNonQuery();
trans.Commit(); // AutoCommit is 'ON'
cmd.Dispose();
conn.Close();

It states in the article that by default it is set to auto commit which has been my experience with mysql as well. This will prevent that from happening.

Try this:

OracleConnection connG = conexiune.conn;
try {
foreach (ListViewItem itm in listView1.Items)
{
string cod;
if (itm.Checked == true)
{
cod = itm.Text;
string delete_sql1 = "delete from furnizor f, comanda c where f.cod_furnizor = c.cod_furnizor and cod_furnizor = :cod_furnizor";
IDbTransaction trans = connG.BeginTransaction();
OracleCommand cmd = new OracleCommand(delete_sql1, connG);
cmd.Parameters.Add(new OracleParameter(":cod_furnizor", Convert.ToInt32(cod)));
cmd.ExecuteNonQuery();
cmd.Dispose();
trans.Commit();
}
}
}
catch (Exception ex)
{
MessageBox.Show(ex.Message.ToString());
}