为什么我提交的数据，弄出来的时候会有重复

[MILKZHOU]

问题：
为什么我提交的数据，弄出来的时候会有重复的呢？怎么解决呢？

先看一下正确的：


但现在却变成这样啦：


涉及到的数据库如下：


涉及的代码如下：

<table width="600" border="0">
  <tr>
    <td><?php  include_once("result_top.php");?></td>
  </tr>
 </table>
 <form action="result_add.php" method="post">
<table width="600" border="1">
    <tr>
    <td>学生姓名</td>
    <td>学号</td>
    <td>性别</td>
    <td>专业</td>
    <td>班级</td>
  </tr>

  <tr>
    <?php
      include_once("conn.php");
      $name = $_POST ['name'];
   $sql="select * from db_stu_info where name='$name'";
   $query = mysql_query($sql) or die("执行sql语句失败".mysql_error());
      if(isset($name))
      {
       $num = mysql_num_rows($query);
   if ($num > 0) {
    while($row = mysql_fetch_array($query))
   {
  ?>
  <!--在input中，增加value的作用就是想在提交的数据库的时候可以提交得到-->
  <td><input name="name" type="hidden" value="<?php echo $row['name'];?>" /><?php echo $row['name'] ?></td>
        <td><input name="num" type="hidden" value="<?php echo $row['num'];?>" ><?php echo $row['num']; ?></td>
        <td><?php echo $row['sex']; ?></td>
        <td><?php echo $row['department']; ?></td>
        <td><?php echo $row['class1']; ?></td>
  <?php
     }
   }
   else{
    echo "<script>alert('没有此学生信息，请重新填写！'); history.back();</script>";
   }
      }
?>
  </tr>
 </table>
 <table border="1"  width="600">
  <tr>
    <td>科目</td>
    <td>成绩</td>
  </tr>
    <?php
   $sql="select b.subject,b.id,db_stu_result.result from db_stu_info a, db_subject b, db_stu_result where a.department=b.department and a.name='$name' order by b.id";
   //SELECT subject,id FROM db_subject WHERE department = (SELECT department FROM db_stu_info WHERE name = '$name')比上式慢
   //作用是：找两个表中先找出department字段一样的，然后再找name字段与POST过来的一样的，找出来的结果用subject来显示
   $query=mysql_query($sql) or die("执行sql语句失败".mysql_error());
      $num = mysql_affected_rows ();
   if ($num > 0) {
     while($row = mysql_fetch_array($query))
   {
    $subject_count=$subject_count.$row["subject"].",";//把所有的科目都赋值给$subject_count
    $subject_id_count=$subject_id_count.$row["id"].",";//把所有的ID号都赋值给$subject_id_count
    $subject_tag=$row["id"];//把ID号赋值给$subject_tag,调用这个就是在调用ID号
  ?>
      <tr>
      <td  width="100"><input name="subject_<?php echo $subject_tag?>" value="<?php echo $row["subject"]?>" type="hidden" ><?php echo $row['subject']?></td>
      <td><input type="text" name="result_<?php echo $subject_tag?>" value="<?php echo $row["result"]?>" /></td>
      </tr>
  <?php
    }
    ?>
     <input name="subject_id" value="<?php echo $subject_id_count?>" type="hidden" ><!--ID-->
     <input name="subject" value="<?php echo $subject_count?>" type="hidden" ><!--科目-->
    <?php
//     echo $subject_count;
//     echo $subject_id_count."<br>";
//     echo $subject_tag;

   }
?>
  <tr>
  <td border="0"  colspan="2"><input type="submit" name="sub" value="提交"/>  <input type="reset"  name="reset" value="重写"></td>
  </tr>
</table>
</form>

[江南昆虫]

应该就是查成绩的sql有问题，db_stu_result缺乏条件约束，试试看：

select b.subject,b.id,(select r.result from db_stu_result r where r.num.a.num and r.subject=b.subject) as result from db_stu_info a, db_subject b where a.name='$name' and b.department=a.department order by b.id

[江南昆虫]

另外，用姓名查询可能会遇到重名问题，应该用学号比较好。

[MILKZHOU]

[Quote=引用 5 楼 jnkc 的回复:]
应该就是查成绩的sql有问题，db_stu_result缺乏条件约束，试试看：
SQL codeselect b.subject,b.id,(select r.resultfrom db_stu_result rwhere r.num.a.numand r.subject=b.subject)as resultfrom db_stu_info a, db_subject bwhere a.name='$name'and b.department=a.departmentorderby b.id
[/Quote]


不行，有错误

[MILKZHOU]

[Quote=引用 6 楼 jnkc 的回复:]
另外，用姓名查询可能会遇到重名问题，应该用学号比较好。
[/Quote]

这个我知道，我只是测试

[MILKZHOU]

结果是这个：

SELECT c.name, b.subject, b.id, c.result
FROM db_stu_info a, db_subject b, db_stu_result c
WHERE a.department = b.department
AND b.subject = c.subject
AND a.name = "朱砂"
ORDER BY id
LIMIT 0 , 30 

[t240034137]

你把你的数据库语句 在数据库中查一下！ 看看什么结果!

[死胖子]

$sql="select b.subject,b.id,db_stu_result.result from db_stu_info a, db_subject b, db_stu_result where a.department=b.department and a.XXX=db_stu_result.XXX and a.name='$name' order by b.id";
//其中XXX是两个表之前的关联字段，如果你两个表中没有关联字段的话，也不能使用NAME做关联字段（应该新增一字段，比如学号），因为容易重名，另外 建议也不要使用（a.name='$name'）来作为条件判断，应该使用学校这样的唯一字段来进行判断

[huang020]

将

$sql="select b.subject,b.id,db_stu_result.result from db_stu_info a, db_subject b, db_stu_result where a.department=b.department and a.name='$name' order by b.id";

换成这句试试

$sql="select b.subject,b.id,db_stu_result.result from db_stu_info a, db_subject b, db_stu_result c where a.department=b.department and c.subject= b.subject and a.name='$name' order by b.id";

你查的是三个表中的约束结果，可你的语句只对两个表做了约束

[MILKZHOU]

这些内容，主要是当我需要修改成绩的时候用的，所以大家可以暂时不要理它

 $subject_count=$subject_count.$row["subject"].",";//把所有的科目都赋值给$subject_count
    $subject_id_count=$subject_id_count.$row["id"].",";//把所有的ID号都赋值给$subject_id_count
    $subject_tag=$row["id"];//把ID号赋值给$subject_tag,调用这个就是在调用ID号

[Siramizu]

看看数据库中是否有重复数据

[MILKZHOU]

[Quote=引用 2 楼 siramizu 的回复:]
看看数据库中是否有重复数据
[/Quote]

没有，我已经删掉了，有重复的话

[MILKZHOU]

我觉得应该是那个SQL有问题吧

select b.subject,b.id,db_stu_result.result from db_stu_info a, db_subject b, db_stu_result where a.department=b.department and a.name='$name' order by b.id