带有参数语法

Question

我有一个模式，其中包含星球大战中的人物列表，他们出现的电影，他们访问的行星等等。这是架构：

CREATE DATABASE  IF NOT EXISTS `starwarsFINAL` /*!40100 DEFAULT CHARACTER SET utf8 */;
USE `starwarsFINAL`;

DROP TABLE IF EXISTS `characters`;
/*!40101 SET @saved_cs_client     = @@character_set_client */;
/*!40101 SET character_set_client = utf8 */;
CREATE TABLE `characters` (
  `character_name` varchar(45) NOT NULL,
  `race` varchar(45) DEFAULT NULL,
  `homeworld` varchar(45) DEFAULT 'Unknown',
  `affiliation` varchar(45) DEFAULT NULL,
  PRIMARY KEY (`character_name`),
   KEY `planet_fk` (`homeworld`),
  CONSTRAINT `planet_fk` FOREIGN KEY (`homeworld`) REFERENCES `planets`     (`planet_name`) ON DELETE SET NULL ON UPDATE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
/*!40101 SET character_set_client = @saved_cs_client */;

DROP TABLE IF EXISTS `movies`;
/*!40101 SET @saved_cs_client     = @@character_set_client */;
/*!40101 SET character_set_client = utf8 */;
CREATE TABLE `movies` (
  `movie_id` int(11) NOT NULL,
  `title` varchar(128) DEFAULT NULL,
  `scenes_in_db` int(11) DEFAULT NULL,
  `scenes_in_movies` int(11) DEFAULT NULL,
  PRIMARY KEY (`movie_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
/*!40101 SET character_set_client = @saved_cs_client */;

DROP TABLE IF EXISTS `planets`;
/*!40101 SET @saved_cs_client     = @@character_set_client */;
/*!40101 SET character_set_client = utf8 */;
CREATE TABLE `planets` (
  `planet_name` varchar(45) NOT NULL,
  `planet_type` varchar(30) DEFAULT NULL,
  `affiliation` varchar(30) DEFAULT NULL,
  PRIMARY KEY (`planet_name`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
/*!40101 SET character_set_client = @saved_cs_client */;

DROP TABLE IF EXISTS `timetable`;
/*!40101 SET @saved_cs_client     = @@character_set_client */;
/*!40101 SET character_set_client = utf8 */;
CREATE TABLE `timetable` (
  `character_name` varchar(45) DEFAULT NULL,
  `planet_name` varchar(45) DEFAULT 'Unknown',
  `movie_id` int(11) DEFAULT NULL,
  `arrival` int(11) DEFAULT NULL,
  `departure` int(11) DEFAULT NULL,
  `time_id` int(11) NOT NULL AUTO_INCREMENT,
  PRIMARY KEY (`time_id`),
  UNIQUE KEY `timetable_un`     (`character_name`,`planet_name`,`movie_id`,`arrival`),
  KEY `timetable_fkplanet` (`planet_name`),
  KEY `timetable_fkmovie` (`movie_id`),
  CONSTRAINT `timetable_fkcharacter` FOREIGN KEY (`character_name`) REFERENCES     `characters` (`character_name`) ON DELETE CASCADE ON UPDATE CASCADE,
  CONSTRAINT `timetable_fkmovie` FOREIGN KEY (`movie_id`) REFERENCES `movies`     (`movie_id`) ON DELETE CASCADE ON UPDATE CASCADE,
  CONSTRAINT `timetable_fkplanet` FOREIGN KEY (`planet_name`) REFERENCES     `planets` (`planet_name`) ON DELETE SET NULL ON UPDATE CASCADE
) ENGINE=InnoDB AUTO_INCREMENT=57 DEFAULT CHARSET=utf8;
/*!40101 SET character_set_client = @saved_cs_client */;

这是我的问题：

  

编写一个接受行星名称并返回的程序track_planet(planet)       包含行星名称，电影名称和数量的结果集       在那部电影中出现在这个星球上的人物。

这是我到目前为止的所作所为，但我已经失去/坚持如何使其发挥作用。 （我是MySQL的新手）

DROP PROCEDURE IF EXISTS track_planet;
DELIMITER $$
CREATE PROCEDURE track_planet(IN planet VARCHAR(45))
BEGIN
    SELECT planet_name FROM planets, title FROM movies, 
    COUNT(DISTINCT character_name) FROM characters WHERE planet_name = planet;
END
DELIMITER;

Answer 1

Hello_ friend。

首先感谢您发布数据库架构确实有帮助。从中我就能拍出这张照片：

我已将您的代码更改为：

DELIMITER $$

DROP PROCEDURE IF EXISTS track_planet $$

CREATE PROCEDURE track_planet(IN planet VARCHAR(45))
BEGIN
    SELECT 
    tt.planet_name as planetName, m.title as movieName, COUNT(tt.character_name) as characters
    FROM timetable tt 
    LEFT JOIN movies m ON tt.movie_id = m.movie_id
    WHERE tt.planet_name = planet
    GROUP BY planetName, movieName;
END $$

DELIMITER ;

除了少量修改之外，函数声明的代码几乎相同。

主要变化是SELECT声明：

1. 选择必要的列;
2. 似乎您拥有timetable内的大部分信息，因此只能加入movies来获取电影名称;
3. 首先在行星名称上使用GROUP BY，然后在电影名称上使用call.enqueue(new Callback<RestaurantsListResponse>() { @Override public void onResponse(Call<RestaurantsListResponse> call, Response<RestaurantsListResponse> response) { if(response.isSuccessful()) { data = new ArrayList<>(); RestaurantsListResponse restaurants = response.body(); Log.d("RestauransActivity", "response = " + new Gson().toJson(restaurants)); data = restaurants.getRestaurants(); Log.d("RestauransActivity", "Items = " + data.size()); RecyclerView recyclerView = (RecyclerView)findViewById(R.id.my_recycler_view); adapter = new MyRecyclerViewAdapter(data); RecyclerView.LayoutManager layoutManager = new LinearLayoutManager(getApplicationContext()); recyclerView.setLayoutManager(layoutManager); recyclerView.setItemAnimator(new DefaultItemAnimator()); recyclerView.setHasFixedSize(true); recyclerView.setAdapter(adapter); } ，以便按特定电影计算特定星球上的字符数

就是这样......

希望这有用。让我知道它是否适合你。

干杯！