MySQL的过程与参数语法

Question

我有星球大战人物名单的模式，看电影，他们出现在，他们参观等。这里的行星是模式：

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 */; 

这里是我的问题：

编写接受行星的名字，并返回 包含行星的名字，电影名，那是电影中的那个星球出现 字符数的结果集的过程track_planet(planet)。

这是我到目前为止，但我失去了/卡住如何使其工作。 （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的架构它确实有帮助。从中我能做出这样的画面：

而且我已经改变了你的代码，以这样的：

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 ; 

的函数声明的代码是相当多的，除了一些修改一样。

主要的变化是SELECT声明：

1. 选择必要的列;
2. 看来你最里面timetable的信息，因此只能加入movies获得电影名称;
3. 使用GROUP BY首先对地球的名称，然后在电影名称，以便将特定影片

指望一个特定的星球人物，就是这样......

希望这是有帮助的。请让我知道这对你有没有用。

干杯！