如何从具有不同条件的表中多次选择同一列 [英] How to select same column more than once from a table with different conditions

问题描述

我有一张桌子：



id student_regno subject_name student_mark类别

1 OIS001英语7作业

2 OIS001 Agric.Sc 6作业

3 OIS001英语15考试

4 OIS001 Agric.Sc 13考试

5 OIS001英语50考试

6 OIS001 Agric.Sc 48考试





我想获取以下记录。



主题名称分配测试考试

英语7 15 50

Agric.Sc 6 13 48





Appreciaite你的帮助。请告诉我这是否可行？如果是，请提供示例SQL。



谢谢



我有什么尝试过：



我使用了以下代码：

  $ sql  =   SELECT student_regno，student_name，academic_session，academic_term，class_abbrev，class_group，subject_name ，student_mark，form_teacher FROM academic_scores WHERE student_regno ='$ student_regno'AND class_name ='$ class_name'AND class_group ='$ class_group'AND academic_session ='$ academic_session'AND academic_term ='$ academic_term'GROUP BY subject_name; 
  $ result  = mysqli_query（$ conn，$ sql）; 
 
 
 while（$ row = $ result-> fetch_assoc（））{
 
 $ subject = $ row ['  subject_name']; 
 
  $ sql1  =   SELECT student_mark FROM academic_scores WHERE student_regno ='$ student_regno'AND class_name ='$ class_name'AND class_group ='$ class_group'AND academic_session ='$ academic_session'AND academic_term ='$ academic_term'AND category ='Assignment' ; 
  $ ress  = mysqli_query（$ conn，$ sql1）; 
 $ row1 = $ ress-> fetch_assoc（）; 
 $ assignment = $ row1 ['  student_mark']; 
 
  $ sql2  =   SELECT student_mark FROM academic_scores WHERE student_regno ='$ student_regno'AND class_name ='$ class_name'AND class_group ='$ class_group'AND academic_session ='$ academic_session'AND academic_term ='$ academic_term'AND category ='Test' ; 
  $ res  = mysqli_query（$ conn，$ sql2）; 
 $ row2 = $ res-> fetch_assoc（）; 
 $ test = $ row2 ['  student_mark']; 
 
  $ sql3  =   SELECT student_mark FROM academic_scores WHERE student_regno ='$ student_regno'AND class_name ='$ class_name'AND class_group ='$ class_group'AND academic_session ='$ academic_session'AND academic_term ='$ academic_term'AND category ='Examination' ; 
  $ res  = mysqli_query（$ conn，$ sql3）; 
 $ row3 = $ res-> fetch_assoc（）; 
 $ exam = $ row3 ['  student_mark']; 
 
 
 
 
  echo  ' < tr> 
< td>'。$ subject。' < / td> 
< td>'。$ assignment。' < / td> 
< td>'。$ test。' < / td> 
< td>'。$ exam。' < / td> 
 
< / tr>'; 
 
 
} 
} 

解决方案

sql = SELECT student_regno，student_name，academic_session，academic_term，class_abbrev，class_group，subject_name，student_mark，form_teacher FROM academic_scores WHERE student_regno ='

student_regno'AND class_name ='

class_name'AND class_group ='

I have a table below:

id student_regno subject_name student_mark category
1 OIS001 English 7 Assignment
2 OIS001 Agric.Sc 6 Assignment
3 OIS001 English 15 Test
4 OIS001 Agric.Sc 13 Test
5 OIS001 English 50 Exam
6 OIS001 Agric.Sc 48 Exam


I want to fetch records as following.

SUBJECT NAME ASSIGNMENT TEST EXAM
English 7 15 50
Agric.Sc 6 13 48


Appreciaite your help. Please tell me if this is possible or not? If yes, can you please provide the sample SQL.

Thanks

What I have tried:

I used the following codes:

$sql = "SELECT student_regno, student_name, academic_session, academic_term, class_abbrev, class_group, subject_name, student_mark,form_teacher FROM academic_scores WHERE student_regno ='$student_regno' AND class_name = '$class_name' AND class_group='$class_group' AND academic_session = '$academic_session' AND academic_term = '$academic_term' GROUP BY subject_name";
       $result = mysqli_query($conn,$sql);


while($row = $result->fetch_assoc()){

        $subject=$row['subject_name'];
      
        $sql1 = "SELECT student_mark FROM academic_scores WHERE student_regno ='$student_regno' AND class_name = '$class_name' AND class_group='$class_group' AND academic_session = '$academic_session' AND academic_term = '$academic_term' AND category='Assignment'";
        $ress = mysqli_query($conn,$sql1);
        $row1=$ress->fetch_assoc();
        $assignment=$row1['student_mark'];

        $sql2 = "SELECT student_mark FROM academic_scores WHERE student_regno ='$student_regno' AND class_name = '$class_name' AND class_group='$class_group' AND academic_session = '$academic_session' AND academic_term = '$academic_term' AND category = 'Test'";
        $res = mysqli_query($conn,$sql2);
        $row2=$res->fetch_assoc();
        $test=$row2['student_mark'];

        $sql3 = "SELECT student_mark FROM academic_scores WHERE student_regno ='$student_regno' AND class_name = '$class_name' AND class_group='$class_group' AND academic_session = '$academic_session' AND academic_term = '$academic_term' AND category = 'Examination'";
        $res = mysqli_query($conn,$sql3);
        $row3=$res->fetch_assoc();
        $exam=$row3['student_mark'];




       echo' <tr>
            <td>'.$subject.'</td>
            <td>'.$assignment.'</td>
            <td>'.$test.'</td>
            <td>'.$exam.'</td>
            
        </tr>';
       

       }
}

解决方案

sql = "SELECT student_regno, student_name, academic_session, academic_term, class_abbrev, class_group, subject_name, student_mark,form_teacher FROM academic_scores WHERE student_regno ='

student_regno' AND class_name = '

class_name' AND class_group='

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