Множественный вывод MySQL

Question

G'day, я начал использовать MySQL сегодня, и у меня возникли проблемы с печально известным 3-х табличным кодом. Все кажется нормально, за исключением того, что я получаю 4 выхода. Мне интересно, может ли кто-нибудь посмотреть мой код и показать мне, почему я получаю 4 из того же выхода.

Вот код:

mysql -u root -p 
show databases; 
drop database if exists Game_Stuff; 
create database Game_Stuff; 
Use Game_Stuff; 

create table mygames(GameID varchar(8) not null primary key, 
Title varchar(20) not null, 
Genre varchar(10) not null, 
Gamedescription varchar(20) not null, 
Gamerating varchar(4) not null, 
Releasedate varchar(10) not null, 
Devid varchar (8) not null, 
CountryID varchar(3) not null); 

insert into mygames(GameID, Title, Genre, Gamedescription, Gamerating, Releasedate, devid, CountryID) values 
('P1', 'Pacman', 'retro', 'map walk around', '80%', '12/12/83', 'Namco', 'Jap'); 

insert into mygames(GameID, Title, Genre, Gamedescription, Gamerating, Releasedate, devid, CountryID) values 
('SF1', 'Street Fighter', 'Old MMA', 'Button masher', '92%', '22/7/88', 'Capcom', 'Jap'); 

insert into mygames(GameID, Title, Genre, Gamedescription, Gamerating, Releasedate, devid, CountryID) values 
('Son1', 'Sonic', 'Platform', 'Reach the end without dying', '95%', '22/7/88', 'Sonic Team', 'Jap'); 

insert into mygames(GameID, Title, Genre, Gamedescription, Gamerating, Releasedate, devid, CountryID) values 
('Mar1', 'Super Mario', 'Platform', 'Rescue Peach', '100%', '13/9/85', 'nintendo', 'Jap'); 

insert into mygames(GameID, Title, Genre, Gamedescription, Gamerating, Releasedate, devid, CountryID) values 
('Berz', 'Berzerk', 'Atari', 'Run and Gun', '100%', '1/1/80', 'Stern', 'USA'); 


insert into mygames(GameID, Title, Genre, Gamedescription, Gamerating, Releasedate, devid, CountryID) values 
('Rnr1', 'runner', 'Atari', 'Run and Gun', '100%', '1/1/80', 'Stern', 'USA'); 


insert into mygames(GameID, Title, Genre, Gamedescription, Gamerating, Releasedate, devid, CountryID) values 
('Rnr12', 'runn4536er', 'Atari', 'Run and Gun', '100%', '1/1/80', 'Stern', 'USA'); 

create table developers(devid varchar(20) not null, 
devcity varchar(25) not null, 
devcountry varchar(20) not null, 
devgames varchar(100) not null, 
devest varchar (10) not null, 
CountryID varchar(3) not null); 

insert into developers(devid, devcity, devcountry, devest, CountryID) values 
('Namco', 'Tokyo', 'Japan', '1/5/55', 'Jap'); 

insert into developers(devid, devcity, devcountry, devest, CountryID) values 
('Capcom', 'Osaka', 'Japan', '11/5/83', 'Jap'); 

insert into developers(devid, devcity, devcountry, devest, CountryID) values 
('Sonic Team', 'Tokyo', 'Japan', '1/1/1990', 'Jap'); 

insert into developers(devid, devcity, devcountry, devest, CountryID) values 
('nintendo', 'Kyoto', 'Japan', '23/8/89', 'Jap'); 

insert into developers(devid, devcity, devcountry, devest, CountryID) values 
('Stern', 'Philadelphia', 'America', '--/--/1946', 'USA'); 

insert into developers(devid, devcity, devcountry, devest, CountryID) values 
('nintendo1', 'Kyoto1', 'Japan', '23/8/89', 'Jap'); 


create table Countries1(CountryID varchar(3) not null primary key, 
Name varchar(25) not null, 
Continent varchar(20) not null); 

insert into Countries1(CountryID, Name, Continent) values 
('Jap', 'Japan', 'Asia'); 

insert into Countries1(CountryID, Name, Continent) values 
('USA', 'America', 'North America'); 

SELECT Title, Name 
FROM Countries1 
inner JOIN developers 
ON Countries1.CountryID = developers.CountryID 
inner JOIN mygames 
ON developers.CountryID = mygames.CountryID 
where Countries1.CountryID = 'Jap'; 

Answer 1

Почему вы даже привлечь разработчиков, если вы только после того, как имя и фамилия?

SELECT Title, Name 
FROM mygames m 
LEFT JOIN Countries1 c 
ON c.CountryID = m.CountryID 
WHERE m.CountryID = 'Jap';