Question

我有这些表格：

single_user_has_university_has_course

single_user_users_id_user   university_has_course_university_id_university  university_has_course_course_id_course  first_year_school   last_year_school grade
1                                               1                                            1                             2000             2001            15

和

university_has_course

university_id_university    course_id_course
    1                           1               <<< I want to select this
    15                          1
    1                           3
    15                          3

问题是下面的查询返回course_id_course = 1 but ignore the university_id_university = 1`的所有行。然后，将返回两行。

查询：

    SELECT A.first_year_school, A.last_year_school, A.grade, U.university, C.course, T.type_course
    FROM single_user_has_university_has_course A

    INNER JOIN university_has_course Q
    ON A.university_has_course_course_id_course  = Q.course_id_course

    INNER JOIN university U
    ON Q.university_id_university  = U.id_university 

    INNER JOIN course C
    ON Q.course_id_course = C.id_course

    INNER JOIN type_course T
    ON C.type_course_id_type_course = T.id_type_course

    AND A.single_user_users_id_user = ?

Answer 1

您正在将最后一个表连接到2个约束C.type_course_id_type_course = T.id_type_course AND A.single_user_users_id_user = ?上的先前联接。我想你想把它写成WHERE子句。所以用以下代码替换你的最后一行：

WHERE A.single_user_users_id_user = ?

但您还没有尝试过滤university_id_university = 1，因此您可能还想将其添加到WHERE子句中：

WHERE A.single_user_users_id_user = ? AND Q.university_id_university = ?

查询无法正常工作

1 个答案: