mysql - SQL：使用多个 SELECT 语句/两次检索相同的字段？

Question

两张表：

person(name,person_id)
lesson(teacher_id, student_id, time, place)

我要检索老师姓名、学生姓名、时间和地点

就像这样：

Teacher|Student|Time|Place
ms bla | fred  | 12 | UK
ms bla | Jim   | 12 | UK
mr ttt | john  | 10 | UNI

ETC..

那么如何选择person_id两次WHERE以匹配teacher-id& student_id？

Answer 1

您可以通过使用别名重命名表（DEMO ）多次加入同一个表：

select
    teacher.name as Teacher,
    student.name as Student,
    lesson.time,
    lesson.place
from
    lesson
join
    person teacher on teacher.person_id = lesson.teacher_id
join
    person student on student.person_id = lesson.student_id

该表通过=lesson链接到person表（别名为teacher）。然后课程表通过=再次链接到表（这次别名为）。通过使用别名，我们可以引用每个别名的列来获取各自的教师和学生姓名。teacher_idperson_idpersonstudentstudent_idperson_idname