public List<Product> queryProduct() { List<Product> products = new List<Product>(); if (OpenDB() != true) return null; MySqlCommand cmd = new MySqlCommand(); cmd.Connection = conn; cmd.CommandText = "select pid,pname,pqgp,pimage,pprice,plocation,pdetail,pnumber,pminimum,tid from (tag natural join tp natural join product)"; try { MySqlDataReader reader = cmd.ExecuteReader(); if (!reader.HasRows) { Console.WriteLine("未查询到相关信息!"); return null; } //FormatPrint("标签ID", "标志位", "商品名称", "商品位置"); while (reader.Read()) { Product product = new Product(); product.setPid(reader[0].ToString()); product.setPname(reader[1].ToString()); product.setPqgp(Convert.ToInt32(reader[2].ToString())); product.setPimage(reader[3].ToString()); product.setPprice(Convert.ToDouble(reader[4].ToString())); product.setPlocation(Convert.ToInt32(reader[5].ToString())); product.setPdetail(reader[6].ToString()); product.setPnumber(Convert.ToInt32(reader[7].ToString())); product.setPminimum(Convert.ToInt32(reader[8].ToString())); product.setTid(reader[9].ToString()); products.Add(product); } } catch (Exception e) { Console.WriteLine("标签查询错误!"); } finally { conn.Close(); } return products; }