我不知道我在使用sql时是否正确执行了以下方法，但是在这里就行了。
我想显示所有考试详细信息（考试详细信息（也称为会议），考试中的问题，答案，罚款，图片，视频等），但是我尝试这样做的方式是一个很大的查询，但它不起作用因为没有显示行。
下面是我要为一项考试（和只有一项考试）显示的内容：
下面显示上面每个部分需要数据库的字段：
考试详细信息
SessionId, SessionName, SessionDuration, TotalMarks, SessionWeight
考试中的所有问题
QuestionId, QuestionNo, QuestionContent, NoofAnswers, QuestionMarks, OptionId, OptionType, ReplyId, ReplyType
每个问题的所有答案并标记每个答案的价值
AnswerId, Answer, AnswerMarks
PenaltyEnabled
PenaltyAnswerId, PenaltyAnswer, PenaltyMarks
ImageId, ImageFile
VideoId VideoFile
AudioId, AudioFile
ModuleId, ModuleNo, ModuleName
StudentId
我的问题是，应该如何编写SQL代码才能显示所有这些数据？我只需要一个大查询还是很多小查询？我的尝试是在问题的底部，但下面是数据库表，该表显示了处理一项考试的详细信息及其所有详细信息。
TABLES：
学生
StudentId (PK) StudentForename StudentSurname
1 James Parker
Student_Session
SessionId (FK) StudentId (FK)
1 1
会话
SessionId (PK) SessionName SessionDuration TotalMarks SessionWeight ModuleId (FK)
1 AAA 01:00:00 30 20 1
模块
ModuleId (PK) ModuleNo ModuleName
1 CHI2513 ICT
问题
SessionId FK) QuestionId (PK) QuestionNo QuestionContent NoofAnswers QuestionMarks OptionId (FK) ReplyId (FK)
1 4 1 Question 1 1 5 1 1
1 5 2 Question 2 1 3 2 1
1 6 3 Question 3 2 6 2 2
1 7 4 Question 4 3 7 5 2
1 8 5 Question 5 1 9 5 1
答案：
AnswerId (PK) Answer QuestionId (FK)
1 A 4
2 C 5
3 A 6
4 B 6
5 B 7
6 D 7
7 E 7
8 G 8
个人回答
IndividualId (PK) AnswerId (FK) AnswerMarks
1 1 3
2 2 5
3 3 3
4 4 3
5 5 2
6 6 2
7 7 3
8 8 9
处罚
PenaltyId(PK) SessionId (FK) PenaltyEnalbed
1 1 1
PenaltyMarks
PenaltyAnswerId (PK) PenaltyAnswer PenaltyMarks QuestionId (FK)
1 B 1 4
2 C 1 4
3 A 1 5
4 B 1 5
5 D 1 5
6 C 2 6
7 D 2 6
8 A 1 7
9 C 1 7
10 F 1 7
11 G 1 7
12 A 0 8
13 B 0 8
14 C 1 8
15 D 1 8
16 E 1 8
17 F 0 8
回复
ReplyId (PK) ReplyType
1 Single
2 Multiple
Option_Table
OptionId (PK) OptionType
1 A-C
2 A-D
3 A-E
4 A-F
5 A-G
图像
ImageId (PK) ImageFile
1 ImageFile/Tulips.png
2 ImageFile/Daisys.png
视频
VideoId (PK) VideoFile
1 VideoFile/Speech.png
音频
AudioId (PK) AudioFile
1 AudioFile/Song.png
Image_Question
ImageQuestionId (PK) ImageId (FK) SessionId (FK) QuestionNo (FK)
1 1 1 2
Video_Question
VideoQuestionId (PK) VideoId (FK) SessionId (FK) QuestionNo (FK)
1 1 1 4
Audio_Question
AudioQuestionId (PK) AudioId (FK) SessionId (FK) QuestionNo (FK)
1 1 1 5
以下是我失败的尝试：
SELECT s.SessionId,
SessionName,
SessionDuration,
TotalMarks,
SessionWeight,
q.QuestionId,
q.QuestionNo,
QuestionContent,
QuestionMarks,
q.OptionId,
OptionType,
q.ReplyId,
ReplyType,
a.AnswerId,
Answer,
NoofAnswers,
AnswerMarks,
PenaltyEnabled,
PenaltyAnswerId,
PenaltyAnswer,
PenaltyMarks,
i.ImageId,
au.AudioId,
v.VideoId,
ImageFile,
AudioFile,
VideoFile,
s.ModuleId,
ModuleNo,
ModuleName,
ss.StudentId
FROM Student st
INNER JOIN Student_Session ss
ON st.StudentId = ss.StudentId
INNER JOIN Session s
ON ss.SessionId = s.SessionId
INNER JOIN Question q
ON s.SessionId = q.SessionId
INNER JOIN Answer a
ON q.QuestionId = a.AnswerId
INNER JOIN Individual_Answer ia
ON a.AnswerId = ia.AnswerId
LEFT JOIN Module m
ON s.ModuleId = m.ModuleId
LEFT JOIN Penalty p
ON q.SessionId = p.SessionId
LEFT JOIN Option_Table o
ON q.OptionId = o.OptionId
LEFT JOIN Reply r
ON q.ReplyId = r.ReplyId
LEFT JOIN Penalty_Marks pm
ON q.QuestionId = pm.QuestionId
LEFT JOIN Image_Question iq
ON q.QuestionId = iq.QuestionNo
INNER JOIN Image i
ON iq.ImageId = i.ImageId
LEFT JOIN Audio_Question aq
ON q.QuestionId = aq.QuestionNo
INNER JOIN Audio au
ON aq.AudioId = au.AudioId
LEFT JOIN Video_Question vq
ON q.QuestionId = vq.QuestionNo
INNER JOIN Video v
ON vq.VideoId = v.VideoId
WHERE s.SessionId = 1
ORDER BY q.QuestionId
更新：
下面的代码将能够在提交问题后将QuestionId插入Image_Question Table ：（这是我在SO上找到的，但已更新为我的表设计）
ImageQuestionToken
{
ImageToken (PK auto)
SessionId
}
Image{
ImageId
ImageFile
}
Image_Question
{
Image_QuestionId
ImageId FK references Image(ImageId)
QuestionId FK references Question(QuestionId)
}
Question
{
QuestionId (PK Auto)
QuestionNo
QuestionContent
....
}
TempImage
{
ImageToken FK references ImageQuestionToken(ImageToken)
ImageFile
}
以及类似的逻辑：
这些表中的外键存在问题：Image_Question，Audio_Question和Video_Question。
您正在使用问题表未索引的问题编号列。我建议将列替换为QuestionId并使用其值。
Image_Question
ImageQuestionId (PK) ImageId (FK) SessionId (FK) QuestionNo(FK)
1 1 1 2
Video_Question
VideoQuestionId (PK) VideoId (FK) SessionId (FK) QuestionNo(FK)
1 1 1 4
Audio_Question
AudioQuestionId (PK) AudioId (FK) SessionId (FK) QuestionNo(FK)
1 1 1 5
您的陈述应如下所示：
SELECT s.SessionId,
SessionName,
SessionDuration,
TotalMarks,
SessionWeight,
q.QuestionId,
q.QuestionNo,
QuestionContent,
QuestionMarks,
q.OptionId,
OptionType,
q.ReplyId,
ReplyType,
a.AnswerId,
Answer,
NoofAnswers,
AnswerMarks,
PenaltyEnabled,
PenaltyAnswerId,
PenaltyAnswer,
PenaltyMarks,
i.ImageId,
au.AudioId,
v.VideoId,
ImageFile,
AudioFile,
VideoFile,
s.ModuleId,
ModuleNo,
ModuleName,
ss.StudentId
FROM Student st
INNER JOIN Student_Session ss
ON st.StudentId = ss.StudentId
INNER JOIN Session s
ON ss.SessionId = s.SessionId
INNER JOIN Question q
ON s.SessionId = q.SessionId
INNER JOIN Answer a
ON q.QuestionId = a.AnswerId
INNER JOIN Individual_Answer ia
ON a.AnswerId = ia.AnswerId
LEFT JOIN Module m
ON s.ModuleId = m.ModuleId
LEFT JOIN Penalty p
ON q.SessionId = p.SessionId
LEFT JOIN Option_Table o
ON q.OptionId = o.OptionId
LEFT JOIN Reply r
ON q.ReplyId = r.ReplyId
LEFT JOIN Penalty_Marks pm
ON q.QuestionId = pm.QuestionId
LEFT JOIN Image_Question iq
ON q.QuestionNo= iq.QuestionNo
LEFT JOIN Image i
ON iq.ImageId = i.ImageId
LEFT JOIN Audio_Question aq
ON q.QuestionNo= aq.QuestionNo
LEFT JOIN Audio au
ON aq.AudioId = au.AudioId
LEFT JOIN Video_Question vq
ON q.QuestionNo= vq.QuestionNo
LEFT JOIN Video v
ON vq.VideoId = v.VideoId
WHERE s.SessionId = 1
ORDER BY q.QuestionId
更新：毕竟，您可以使用“问题否”列，只需添加索引即可，而不必检查代码。 [呵呵呵
我建议您添加此：
ALTER TABLE `your_schema`.`Question`
ADD INDEX `your_idx` (`QuestionNo` ASC);
而不是这些：
LEFT JOIN Image_Question iq
ON q.QuestionId = iq.QuestionId -- from iq.QuestionNo
LEFT JOIN Image i
ON iq.ImageId = i.ImageId
LEFT JOIN Audio_Question aq
ON q.QuestionId = aq.QuestionId -- from aq.QuestionNo
LEFT JOIN Audio au
ON aq.AudioId = au.AudioId
LEFT JOIN Video_Question vq
ON q.QuestionId = vq.QuestionId -- from vq.QuestionNo
LEFT JOIN Video v
ON vq.VideoId = v.VideoId
您使用这些：
LEFT JOIN Image_Question iq
ON q.QuestionNo= iq.QuestionNo
LEFT JOIN Image i
ON iq.ImageId = i.ImageId
LEFT JOIN Audio_Question aq
ON q.QuestionNo= aq.QuestionNo
LEFT JOIN Audio au
ON aq.AudioId = au.AudioId
LEFT JOIN Video_Question vq
ON q.QuestionNo= vq.QuestionNo
LEFT JOIN Video v
ON vq.VideoId = v.VideoId
虽然我不是100％地确定您想要的确切结果。根据您现有的查询，问题在于应该使用INNER JOIN时在某些表上使用LEFT JOIN。
在现有查询中，您正在使用以下内容：
LEFT JOIN Image_Question iq
ON q.QuestionId = iq.QuestionNo
INNER JOIN Image i
ON iq.ImageId = i.ImageId
LEFT JOIN Audio_Question aq
ON q.QuestionId = aq.QuestionNo
INNER JOIN Audio au
ON aq.AudioId = au.AudioId
LEFT JOIN Video_Question vq
ON q.QuestionId = vq.QuestionNo
INNER JOIN Video v
ON vq.VideoId = v.VideoId
问题是INNER JOIN正在检查所有字段上的匹配记录，但您可能没有image，audio或video表中存在的记录，因此它不返回任何内容。
根据您的详细信息，您的查询应与此类似：
select st.studentid,
s.sessionid,
s.sessionname,
s.sessionduration,
s.totalmarks,
s.sessionweight,
q.questionid,
q.questionno,
q.questioncontent,
q.noofanswers,
q.questionmarks,
q.optionid,
ot.optiontype,
q.replyid,
r.replytype,
a.answerid,
a.answer,
ia.answermarks,
p.penaltyenabled,
pm.penaltyanswerid,
pm.penaltyanswer,
pm.penaltymarks,
i.imageid,
i.imagefile,
v.videoid,
v.videofile,
ad.audioid,
ad.audiofile,
m.moduleid,
m.moduleno,
m.modulename
from Student st
inner join Student_Session ss
on st.studentid = ss.studentid
inner join session s
on ss.sessionid = s.sessionid
inner join question q
on s.sessionid = q.sessionid
inner join answer a
on q.questionid = a.questionid
inner join Individual_Answer ia
on a.answerid = ia.answerid
left join Option_Table ot
on q.optionid = ot.optionid
left join reply r
on q.replyid = r.replyid
left join module m
on s.moduleid = m.moduleid
left join Penalty p
on s.sessionid = p.sessionid
left join penalty_marks pm
on q.questionid = pm.questionid
left join image_question iq -- note I am joining on both session and question
on s.sessionid = iq.sessionid
and q.questionid = iq.questionno
left join image i -- this should be a left join not inner join
on iq.imageid = i.imageid
left join video_question vq -- note I am joining on both session and question
on s.sessionid = vq.sessionid
and q.questionid = vq.questionno
left join video v -- this should be a left join not inner join
on vq.videoid = v.videoid
left join audio_question aq -- note I am joining on both session and question
on s.sessionid = aq.sessionid
and q.questionid = aq.questionno
left join audio ad -- this should be a left join not inner join
on aq.audioid = ad.audioid
where s.SessionId = 1
order by q.QuestionId
这将返回您上面要求的所有数据。样本：
| STUDENTID | SESSIONID | SESSIONNAME | SESSIONDURATION | TOTALMARKS | SESSIONWEIGHT | QUESTIONID | QUESTIONNO | QUESTIONCONTENT | NOOFANSWERS | QUESTIONMARKS | OPTIONID | OPTIONTYPE | REPLYID | REPLYTYPE | ANSWERID | ANSWER | ANSWERMARKS | PENALTYENABLED | PENALTYANSWERID | PENALTYANSWER | PENALTYMARKS | IMAGEID | IMAGEFILE | VIDEOID | VIDEOFILE | AUDIOID | AUDIOFILE | MODULEID | MODULENO | MODULENAME |
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| 1 | 1 | AAA | 01:00:00 | 30 | 20 | 4 | 1 | Question 1 | 1 | 5 | 1 | A-C | 1 | Single | 1 | A | 3 | 1 | 1 | B | 1 | (null) | (null) | 1 | VideoFile/Speech.png | (null) | (null) | 1 | CHI2513 | ICT |
| 1 | 1 | AAA | 01:00:00 | 30 | 20 | 4 | 1 | Question 1 | 1 | 5 | 1 | A-C | 1 | Single | 1 | A | 3 | 1 | 2 | C | 1 | (null) | (null) | 1 | VideoFile/Speech.png | (null) | (null) | 1 | CHI2513 | ICT |
| 1 | 1 | AAA | 01:00:00 | 30 | 20 | 5 | 2 | Question 2 | 1 | 3 | 2 | A-D | 1 | Single | 2 | C | 5 | 1 | 3 | A | 1 | (null) | (null) | (null) | (null) | 1 | AudioFile/Song.png | 1 | CHI2513 | ICT |
| 1 | 1 | AAA | 01:00:00 | 30 | 20 | 5 | 2 | Question 2 | 1 | 3 | 2 | A-D | 1 | Single | 2 | C | 5 | 1 | 5 | D | 1 | (null) | (null) | (null) | (null) | 1 | AudioFile/Song.png | 1 | CHI2513 | ICT |
| 1 | 1 | AAA | 01:00:00 | 30 | 20 | 5 | 2 | Question 2 | 1 | 3 | 2 | A-D | 1 | Single | 2 | C | 5 | 1 | 4 | B | 1 | (null) | (null) | (null) | (null) | 1 | AudioFile/Song.png | 1 | CHI2513 | ICT |
关键问题：通常，使用外部联接表的内部联接不会返回任何行
我已经使用Microsoft SQL语法进行了子查询。希望能帮助到你。请参阅底部的警告，并根据需要忽略创建过程语句，而只需在顶部声明@SessionID并将其设置为1。
create procedure GetStuff(
@SessionID as integer
) as
declare @StudentID int -- you may need to use a different data type
select @StudentID = StudentID from Student_Session where SessionID = @SessionID
-- now we can at least remove the sessions table from the join list.
SELECT s.SessionId,
SessionName,
SessionDuration,
TotalMarks,
SessionWeight,
q.QuestionId,
q.QuestionNo,
QuestionContent,
QuestionMarks,
q.OptionId,
OptionType,
q.ReplyId,
ReplyType,
a.AnswerId,
Answer,
NoofAnswers,
AnswerMarks,
PenaltyEnabled,
PenaltyAnswerId,
PenaltyAnswer,
PenaltyMarks,
i.ImageId,
au.AudioId,
v.VideoId,
ImageFile,
AudioFile,
VideoFile,
s.ModuleId,
ModuleNo,
ModuleName,
ss.StudentId
FROM Student st
INNER JOIN Student_Session ss
ON st.StudentId = ss.StudentId
INNER JOIN Session s
ON ss.SessionId = s.SessionId
INNER JOIN Question q
ON s.SessionId = q.SessionId
INNER JOIN Answer a
ON q.QuestionId = a.AnswerId
INNER JOIN Individual_Answer ia
ON a.AnswerId = ia.AnswerId
LEFT outer JOIN Module m
ON s.ModuleId = m.ModuleId
LEFT outer JOIN Penalty p
ON q.SessionId = p.SessionId
LEFT outer JOIN Option_Table o
ON q.OptionId = o.OptionId
LEFT outer JOIN Reply r
ON q.ReplyId = r.ReplyId
LEFT outer JOIN Penalty_Marks pm
ON q.QuestionId = pm.QuestionId
-- you can't inner join off of an outer joined table, or you'll get no rows for the entire query. I've nested the query, which is bad practice but... practical for getting this monster of a query working.
LEFT outer JOIN (select c3.ImageID, c3.ImageFile from Image_Question as a1 inner join Images as b1 on a1.QuestionNo = b1.QuestionNo inner join Image as c1 on a1.ImageID = c1.ImageID)
ON q.QuestionID = iq.QuestionID
-- you can't inner join off of an outer joined table, or you'll get no rows for the entire query. I've nested the query, which is bad practice but... practical for getting this monster of a query working.
LEFT outer JOIN (select b2.AudioID, b2.AudioFile from Audio_Question as a2 inner join Audio as b2 on a2.AudioID = b2.AudioID) as aq
ON q.QuestionId = aq.QuestionNo
-- you can't inner join off of an outer joined table, or you'll get no rows for the entire query. I've nested the query, which is bad practice but... practical for getting this monster of a query working.
left outer join (select b3.VideoID, b3.VideoFile from Video_Question as a3 inner join Video as b3 on a3.QuestionID = b3.QuestionID) as vq
WHERE
st.StudentID = @StudentID
and
s.SessionId = @SessionID
ORDER BY q.QuestionId
go
警告：您真的很想将其分解为单独的香料，以便在客户端应用程序中显示。例如，您需要显示Exams和ExamDetails的主/详细信息显示，否则，您将不得不抑制显示给用户的输出中的重复值。例如，从概念上讲，您的输出应如下所示：
<Exam Detail Fields> <Exam Detail Fields>
first one unique What is the color of your DOG?
repeat What is the color of your CAT?
repeat What is the color of your CAR?
repeat What is the color of your HAT?
请注意您必须禁止显示的左侧重复值。
好吧，尝试一下小小的尝试：我的意思是：-逐步执行查询首先删除一些联接（删除大多数联接），然后一个接一个地添加它们，我对大型查询执行相同的操作以跟踪实际问题出在哪里，或者哪些条件对获取结果行产生了主要影响。只是一个想法。干杯!
我认为
LEFT JOIN Image_Question iq
ON q.QuestionId = iq.QuestionNo
将为您提供空值
由于q.QuestionId从4开始，而iq.QuestionNo为2
INNER JOIN Image i
ON iq.ImageId = i.ImageId
并且Iq字段中所有由左外部联接产生的值均为空。因此，对它们进行的任何内部联接都可以为您提供空结果。