how to select id from one table to anothter table

MySqlConnection exclecon = new MySqlConnection("Server=Localhost;DataBase=password1;user=root;password=nectar");
                   exclecon.Open();
                   MySqlCommand cmdYear = new MySqlCommand("INSERT INTO slayear (YEAR) VALUES(@YEAR)", exclecon);
                   cmdYear.Parameters.AddWithValue("@YEAR", YEAR);
                   MySqlCommand cmdMonth = new MySqlCommand("INSERT INTO slamonth (MONTH,contenttype) VALUES(@MONTH,@contenttype)=(select idyear from slayear where idyear=@idyear)  ", exclecon);
                   cmdMonth.Parameters.AddWithValue("@MONTH", MONTH);
                   cmdMonth.Parameters.Add("@contenttype", MySqlDbType.VarChar).Value = contenttype;

                   cmdYear.ExecuteNonQuery();
                   cmdMonth.ExecuteNonQuery();