Question

我有4个表格

student
-------
id, int
firstName, varchar
lastName, varchar

course
------
id, int
name, varchar

semester
--------
id, int
name, varchar

mark
----
studentId, int
courseId, int
semesterId, int
mark, int

我想作一个 s问,再保留firstName,lastName,ario Name,semesterName和>,在mark的表格中各行各加标>。



我试图与INNER JOIN一道这样做,但我可以把INNER JOIN列入一个以上表格。

That code I reached finally

select student.firstName, student.lastName, course.name, semester.name, mark.mark
from mark
INNER JOIN student ON student.id = mark.studentId
INNER JOIN course ON course.id = mark.courseId
INNER JOIN semester ON semester.id = mark.semesterId

Answer 1

在准入女士中,你必须把亲子纳入一个与多个方面合并的询问:

select st.firstName, st.lastName, c.name, sm.name, m.mark
from (((mark m
        INNER JOIN student st ON st.id = m.studentId)
        INNER JOIN course c ON c.id = m.courseId)
        INNER JOIN semester sm ON sm.id = m.semesterId)

Answer 2

Try theta style join:

select student.firstName, student.lastName, course.name, semester.name, mark.mark
from mark, student ,course, semester
WHERE  student.id = mark.studentId AND course.id = mark.courseId AND semester.id = mark.semesterId

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