联盟?相交?或倒置相交

Question

我正在研究一个选择语句，该语句应该返回每个上学日的类。在周期重新开始之前有 4 个上学日。（例如星期一 = 第 1 天，星期二 = 第 2 天...星期四 = 第4天，星期五 = 第1天。等）

有些学生在某些日子可能会休息 1 节课，在这种情况下，我们应该在该天/经期组合上显示一个空白区域。

目前，select 语句仅返回具有值的天数。

例：

            Day 1    Day 2    Day 3    Day 4
Period 1    class    class    off      class
Period 2    class    class    class    off
Period 3    off      class    class    class
Period 4    class    off      class    class

我试图完成的是让 select 语句返回一个空行（带有空值）来代替某一天关闭的时间段。我尝试添加以日期作为唯一值的联合。

这不起作用，因为我得到了我的前 3 行，然后是其他 4 行，但我真正想要的是前 3 行（例如，第 1,3,4 天）和最后一行（例如第 2 天），在这种情况下，我可以在当天之前下订单。

我该怎么做？我应该使用相交吗？ ..还是相交的反面？这也是针对 Oracle 数据库的。

选择语句：

select spct.course_code||'-'||spct.course_section as course,t.school_cycle_day as jour,p.legal_first_name,p.legal_surname,sc.room_no
from   student_program_class_tracks@trl spct,class_meetings@trl cm,school_classes@trl sc,persons@trl p,timeslots@trl t,school_timeline_periods@trl tsp
where  spct.school_code=cm.school_code
and    spct.school_code=sc.school_code
and    spct.school_code=t.school_code
and    spct.school_code=tsp.school_code
and    spct.school_year=cm.school_year
and    spct.school_year=sc.school_year
and    spct.school_year=t.school_year
and    spct.school_year=tsp.school_year
and    t.school_year_track=tsp.school_year_track
and    t.school_timeline_code=tsp.school_timeline_code
and    t.school_period=tsp.school_period
and    spct.class_code=cm.class_code
and    spct.class_code=sc.class_code
and    sc.reporting_teacher=p.person_id
and    cm.block=t.block
and    spct.school_code='73'
and    spct.school_year='20122013'
and    spct.person_id='000170629'
and    cm.semester='2'
and    cm.term='1'
and    t.school_period='1'
and    ((spct.start_date <= sysdate and spct.end_date >= sysdate) or spct.demit_indicator='0')
--order by t.school_cycle_day
UNION
SELECT '','1','','','' from DUAL
UNION
SELECT '','2','','','' from DUAL
UNION
SELECT '','3','','','' from DUAL
UNION
SELECT '','4','','','' from DUAL;

输出：

Course         Jour    Legal_first_name   Legqal_surname     Room_no
PPL4OO-03      2       François           Belle-Isle     1-139
SBI4UU-02      4       Louise             Bérubé             1-155
TFC4EE-02      3       Gino               Proulx             1-127
           1            

感谢您提供的任何帮助！

Answer 1

如果您所说的是您希望每个学生有 4 行，那么应该像下面这样的事情就可以了。

SELECT
    B.course
    A.school_cycle_day,
    B.legal_first_name,
    B.legal_surname,
    B.room_no
FROM
    (
        SELECT '1' AS school_cycle_day
        FROM DUAL
        UNION ALL
        SELECT '2'
        FROM DUAL
        UNION ALL
        SELECT '3'
        FROM DUAL
        UNION ALL
        SELECT '4'
        FROM DUAL
    ) A
    LEFT JOIN
   (
      select
           spct.course_code||'-'||spct.course_section as course,
           t.school_cycle_day as jour,
           p.legal_first_name,
           p.legal_surname,
           sc.room_no
      from
           student_program_class_tracks@trl spct,
           class_meetings@trl cm,
           school_classes@trl sc,
           persons@trl p,
           timeslots@trl t,
           school_timeline_periods@trl tsp
      where
           spct.school_code=cm.school_code and
           spct.school_code=sc.school_code and
           spct.school_code=t.school_code and
           spct.school_code=tsp.school_code and
           spct.school_year=cm.school_year and
           spct.school_year=sc.school_year and
           spct.school_year=t.school_year and
           spct.school_year=tsp.school_year and
           t.school_year_track=tsp.school_year_track and
           t.school_timeline_code=tsp.school_timeline_code and
           t.school_period=tsp.school_period and
           spct.class_code=cm.class_code and
           spct.class_code=sc.class_code and
           sc.reporting_teacher=p.person_id and
           cm.block=t.block and
           spct.school_code='73' and
           spct.school_year='20122013' and
           spct.person_id='000170629' and
           cm.semester='2' and
           cm.term='1' and
           t.school_period='1' and
           ((spct.start_date <= sysdate and spct.end_date >= sysdate) or  spct.demit_indicator='0')
) B ON A.school_cycle_day = B.school_cycle_day