Question

我在mysql中有这个表，但不知道如何以我所需的格式显示结果。

标记（表）

ID     student_id      class_id     subject_id     obtained_marks       total_marks
1          1               1            11               68                  100     
2          2               1            11               63                  100     
3          3               1            11               61                  100     
4          1               1            12               45                  100     
5          2               1            12               75                  100     
6          3               1            12               61                  100     
7          1               1            13               42                  100     
8          2               1            13               84                  100     
9          3               1            13               78                  100

其中subject_id 11 =英语，12 =数学，13 =科学。现在我想显示那样的结果表

Student_id        English      Math      Science    
     1              68          63         61        
     2              45          75         84        
     3              61          61         78

有谁能告诉我如何形成这种查询？

Answer 1

尝试pivoting data like this

Select * from table
    Pivot
    (
    Max (obtainedmarks)
    For studentid in ([english],[math],[science])
    )
    Group by studentid

Answer 2

在mysql中进行数据透视的最好方法，虽然我没有尝试过你的情况，但下面的sql应该可以正常工作

 select 
    student_id,
    SUM(english) as english,
    SUM(math) as math,
    SUM(science) as science
    FROM (
    SELECT 
    student_id,
    CASE WHEN  subject_id = 11 THEN  obtained_marks else 0  end as English , 
    CASE WHEN  subject_id = 12 THEN  obtained_marks else 0  end as Math , 
    CASE WHEN  subject_id = 13 THEN  obtained_marks else 0  end as science 
    from marks
    )tmp
group by student_id

你可以运行像

这样的查询

select * from subjects

动态创建下面的SQL

    CASE WHEN  subject_id = 11 THEN  obtained_marks else 0  end as English , 
    CASE WHEN  subject_id = 12 THEN  obtained_marks else 0  end as Math , 
    CASE WHEN  subject_id = 13 THEN  obtained_marks else 0  end as science

即

foreach($subject as $id=>$name){
  $sql.=CASE WHEN  subject_id = $id THEN  obtained_marks else 0  end as $name, 

}

Answer 3

 select t.student_id,sum(t.english) as  English,sum(t.maths) as  Maths,
        sum(t.science) as Science from
     (select student_id,case when subject_id=11 then obtained_marks else 0 end as english,
       case when subject_id =12 then obtained_marks else 0 end as maths,
       case when subject_id =13 then obtained_marks else 0 end as science from Marks) as 
       t group by t.student_id

Answer 4

您应该像这样更改表格结构

ID     student_id      class_id     english_marks   Maths_marks  science_marks
1          1               1            11               68           55

然后你可以在它的方面获取每一行TABLE HEAD

 <table>
<th>Student_id</th>
<th>English</th>
<th>Math</th>
<th>Science<th>

while($fetch = mysql_fetch_array($sql))
{
    echo '<td>'.$fetch[student_id].'</td>';
echo '<td>'.$fetch[english_marks].'</td>';
echo '<td>'.$fetch[Maths_marks].'</td>';
echo '<td>'.$fetch[science_marks].'</td>';

}

</table>

这是一种很好的方法：）

在mysql表中创建结果表

4 个答案: