Question

different option

我有三个选项，你可以看到。我只需要课程选项和年份选项。现在我想获取它们的值，以便我可以将它们传递给我的查询。这里的问题是，它们是基于不同的表进行查询的，当我尝试将Section的$ _POST传递给变量并查询它时，错误表明未定义的索引。我该怎么办？感谢

这是两个选项的代码：

<div class="col-md-3 pull right">
              <label>Course</label>
                <select class="form-control" name="course" id="courseselect">
                    <?php
                         $query= mysqli_query($con,"SELECT * FROM course");
                         $numrows=mysqli_num_rows($query);
                      if($numrows !=0 ){
                          while($row=mysqli_fetch_assoc($query)) {?>
                           <option value="<?php echo $row['courseid'];?>"><?php echo $row['coursedesc'];?></option>
                          <?php } 
                        }
                      ?> 

                </select>
                </div>

          <div class="col-md-2 pull right">
             <label>Year</label>
                <select class="form-control" name="year">
                   <?php
                     $query= mysqli_query($con,"SELECT * FROM year");
                    $numrows=mysqli_num_rows($query);
                   if($numrows !=0 ){
                          while($row=mysqli_fetch_assoc($query)) {?>
                          <option ><?= $row['yearnum'];?></option>
                          <?php } 
                        }
                  ?>
                </select>
            </div>

这是我的查询

$cid=$_POST['courseid'] //the value from the Course option
SELECT t1.studentno, t1.firstname, t1.lastname, t1.yearid, t2.coursedesc
                    FROM
                        students as t1
                        INNER JOIN course as t2
                            ON $cid=t2.courseid
                        LEFT JOIN paidstudents as t3
                            ON t1.studentno = t3.studentno
                    WHERE
                        t1.studentno IS NOT NULL
                        AND t3.studentno IS  NULL

$ cid表示未定义的索引

我想将courseid和yearid替换为上面的post值。谢谢

Answer 1

您的表单选择是：

<select class="form-control" name="course" id="courseselect">

所以发布的字段为course，但在您的代码中执行：

$cid=$_POST['courseid']

所以要么

$cid = $_POST['course'];

或

<select class="form-control" name="courseid" id="courseselect">

使表单字段名称与您尝试访问的POST变量匹配。

获取不同选项

1 个答案: