mysql - on 子句中的列 'id_training' 不明确

Question

这个问题已经有答案了:

MySQL 'user_id' in where clause is ambiguous problem (4 个答案)

已关闭 4 年前。

我想显示 course_title 数据，但我得到:

'id_training' in on clause is ambiguous.

查询错误在哪里？

CREATE TABLE `examination` (
`id_exam` int(32) NOT NULL,  
`class_name` varchar(100) NOT NULL,
`id_training` int(32) NOT NULL, 
`id_question` int(32) NOT NULL,
`total` int(3) NOT NULL,  
`exam_duration` int(5) NOT NULL,
`start` datetime NOT NULL,
`end` datetime NOT NULL,
`passing_grade` int(3) NOT NULL,
`id_user` int(32) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

CREATE TABLE `training` (
`id_training` int(32) NOT NULL,  
`course_code` varchar(25) NOT NULL,
`course_title` varchar(100) NOT NULL,
`training_time` int(11) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

查询:

SELECT e.id_exam
     , e.class_name
     , e.id_training
     , e.total
     , e.exam_duration
     , e.start_exam
     , e.end_exam
     , e.passing_grade
     , t.course_title 
FROM examination e
INNER JOIN training t
ON id_training = course_tilte

Answer 1

此错误“on 子句中的列 'id_training' 不明确”的原因两个表中存在相同的列，因此由于指定where 子句 sql 中的 id_training 列对我应该采用哪个表感到困惑，因此始终使用别名指定。

SELECT e.id_exam
     , e.class_name
     , e.id_training
     , e.total
     , e.exam_duration
     , e.start_exam
     , e.end_exam
     , e.passing_grade
     , t.course_title 
  FROM examination e
  JOIN training t
    ON e.id_training = t.id_training