为什么我在字段列表中得到错误的字段或未知列？

Question

我创建了这两个表：

CREATE TABLE `Game` (

 `GameName` varchar(30) NOT NULL,
 `GameGenre` varchar(20) NOT NULL,
 `GameDescription` varchar(500) NOT NULL,
 `GameMode` varchar(20) NOT NULL,
 PRIMARY KEY (`GameName`)
) ENGINE=InnoDB;

CREATE TABLE `GameScoreTotal` (

 `ScoreID` int(3) NOT NULL AUTO_INCREMENT,
 `GameName` varchar(30) NOT NULL,
 `OverallScoreTotal` mediumint(9) NOT NULL,
 `GraphicsTotal` mediumint(9) NOT NULL,
 `StoryTotal` mediumint(9) NOT NULL,
 `GameplayTotal` mediumint(9) NOT NULL,
 `TimeTotal` mediumint(9) NOT NULL,
 PRIMARY KEY (`ScoreID`),
  CONSTRAINT  FOREIGN KEY (`GameName`) REFERENCES `Game` (`GameName`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB;

我的查询需要根据GameScoreTotal.OverallScoreTotal返回前十场比赛的游戏桌中的所有信息。

我试过的查询：

SELECT GameName 
FROM Game 
FULL JOIN GameScoreTotal 
    ON Game.GameName=GameScoreTotal.GameName 
ORDER BY OverallScoreTotal DESC 
LIMIT 0, 10;

SELECT Game.GameName 
FROM Game 
FULL JOIN GameScoreTotal 
    ON Game.GameName=GameScoreTotal.GameName 
ORDER BY OverallScoreTotal DESC 
LIMIT 0, 10;

两个表都包含合法记录。

Answer 1

查询1

在您的第一个查询中，问题是GameName和GameScoreTotal表中都存在GameName字段。因此错误Column 'GameName' in field list is ambiguous

查询2

MySQL没有 FULL JOIN 。 Read here关于MySQL JOIN语法。

在游戏和 GameScoreTotal 表之间尝试 LEFT OUTER JOIN ，此联接将从Game表中获取所有记录以及所有匹配来自 GameScoreTotal 表的记录，如果 GameScoreTotal 表中没有匹配的记录，则会显示NULL。

您还可以尝试 INNER JOIN ，它只会获取两个表之间的匹配记录。

脚本：

SELECT Game.GameName 
FROM Game 
LEFT OUTER JOIN GameScoreTotal 
    ON Game.GameName=GameScoreTotal.GameName 
ORDER BY OverallScoreTotal DESC 
LIMIT 0, 10;