Go语言开发点餐系统中的菜品分类功能实现方法

  db, err := sql.Open("mysql", "username:passWord@tcp(127.0.0.1:3306)/database_name")
  if err != nil {
      log.Fatal(err)
  }
  defer db.Close()

  func GetCategories() ([]Category, error) {
      var categories []Category
      rows, err := db.Query("SELECT id, name FROM category")
      if err != nil {
          return nil, err
      }
      defer rows.Close()

      for rows.Next() {
          var c Category
          if err := rows.Scan(&c.ID, &c.Name); err != nil {
              return nil, err
          }
          categories = append(categories, c)
      }
      
      return categories, nil
  }

  func GetMenuByCategory(categoryID int) ([]Menu, error) {
      var menu []Menu
      rows, err := db.Query("SELECT id, name, price FROM menu WHERE category_id = ?", categoryID)
      if err != nil {
          return nil, err
      }
      defer rows.Close()
      
      for rows.Next() {
          var m Menu
          if err := rows.Scan(&m.ID, &m.Name, &m.Price); err != nil {
              return nil, err
          }
          menu = append(menu, m)
      }
      
      return menu, nil
  }

  func main() {
      categories, err := GetCategories()
      if err != nil {
          log.Fatal(err)
      }
      
      for _, c := range categories {
          fmt.Println("分类：" + c.Name)
          menu, err := GetMenuByCategory(c.ID)
          if err != nil {
              log.Fatal(err)
          }
          for _, m := range menu {
              fmt.Println("菜品：" + m.Name, "价格：" + strconv.Itoa(m.Price))
          }
          
          fmt.Println("--------------")
      }
  }