public string mdb_exe_return(string sql)
{
data_conn cn = new data_conn();
OleDbConnection connection1 = cn.mdb_conn();
OleDbCommand command1;
connection1.Open();
OleDbDataAdapter da = new OleDbDataAdapter();
DataSet ds = new DataSet();
command1 = new OleDbCommand(sql, connection1);
command1.ExecuteNonQuery();
command1 = new OleDbCommand("select @@identity", connection1);
da.SelectCommand = command1;
da.Fill(ds, "aa");
connection1.Close();
return ds.Tables["aa"].Rows[0][0].ToString();
}