我在php和ajax中有一个工作下拉列表，我得到学年的id将它传递给另一个是Curriculum.php的页面。我的问题是如何自动选择学年ID，如下面的截图。
我尝试过使用但不会下拉。您需要在年级下拉前选择学年
我有这段代码：
的index.php
<div class="col-xl-6">
<div class="card pd-20 pd-sm-30 form-layout form-layout-4">
<h6 class="card-body-title mg-b-45">Add Subject</h6>
<!-- <p class="mg-b-20 mg-sm-b-45">Add subject for curriculum</p> -->
<div class="row">
<label class="col-sm-4 form-control-label">School Year: <span class="tx-danger">*</span></label>
<div class="col-sm-8 mg-t-10 mg-sm-t-0">
<select class="form-control select2" id="sy" data-placeholder="Select grade level" disabled>
<option label="Select grade level"></option>
<?php
$id = $_GET['id'];
include('../includes/db_conn.php');
$q = mysqli_query($conn,"SELECT * FROM tbl_curriculum JOIN tbl_school_year ON tbl_curriculum.sy_id = tbl_school_year.sy_id WHERE tbl_school_year.sy_id = {$id} GROUP BY tbl_school_year.sy_id");
while($row=mysqli_fetch_array($q)){
echo '<option value="'.$row['sy_id'].'" selected>'.$row['sy_start'].' - '.$row['sy_end'].'</option>';
}
?>
</select><!-- end select -->
</div>
</div><!-- row -->
<div class="row mg-t-20">
<label class="col-sm-4 form-control-label">Grade Level: <span class="tx-danger">*</span></label>
<div class="col-sm-8 mg-t-10 mg-sm-t-0">
<select class="form-control select2" name="cur_id" id="grade_cur" data-placeholder="Select grade level">
<option label="Select grade level"></option>
</select>
</div>
</div>
<div class="row mg-t-20">
<label class="col-sm-4 form-control-label">Subject: <span class="tx-danger">*</span></label>
<div class="col-sm-8 mg-t-10 mg-sm-t-0">
<select class="form-control select2" data-placeholder="Select subject" id="subject" name="subject_id[]" multiple>
</select>
</div>
</div>
<div class="row mg-t-20">
<label class="col-sm-4 form-control-label">Add More: <span class="tx-danger">*</span></label>
<div class="col-sm-6 mg-t-10 mg-sm-t-0">
<input class="form-control" placeholder="Add Subject" type="text">
</div>
<a href="#" class="btn btn-success btn-icon mg-r-5 mg-b-10"><div><i class="fa fa-plus"></i></div></a>
</div>
<div class="form-layout-footer mg-t-30">
<button class="btn btn-success mg-r-5" name="add_cur_subj" value="submit">Add Subject</button>
<?php
$id = $_GET['id'];
$sel = "SELECT * FROM tbl_school_year
WHERE tbl_school_year.sy_id = {$id} GROUP BY tbl_school_year.sy_id";
$result = mysqli_query($conn,$sel);
while($row = mysqli_fetch_assoc($result)){
?>
<a href="reg-assign-section.php?id=<?php echo $row['sy_id']?>" class="btn btn-success">Next <i class="fa fa-arrow-circle-o"></i><i class="fa fa-arrow-circle-o-right"></i></a>
<?php }?>
<button class="btn btn-secondary">Cancel</button>
</div><!-- form-layout-footer -->
</div><!-- card -->
</form>
</div><!-- col-6 -->
ajaxdropdown.php
<script type="text/javascript">
//dropdown for grade level
$(document).ready(function(){
$('#sy').on('change',function(){
var sy_ID = $(this).val();
if(sy_ID){
$.ajax({
type:'POST',
url:'./functions/dd_add_cur.php',
data:'sy_id='+sy_ID,
success:function(html){
$('#grade_cur').html(html);
$('#section').html('<option value="">Select grade_cur first</option>');
}
});
}else{
$('#grade_cur').html('<option value="">Select country first</option>');
$('#section').html('<option value="">Select grade_cur first</option>');
}
});
//dropdown for section
$('#grade_cur').on('change',function(){
var curID = $(this).val();
if(curID){
$.ajax({
type:'POST',
url:'functions/dd_add_cur.php',
data:'cur_id='+curID,
success:function(html){
$('#subject').html(html);
}
});
}else{
$('#subject').html('<option value="">Select country first</option>');
}
});
});
</script>
dd_add_cur.php
<?php
//Include database configuration file
include('../../includes/db_conn.php');
if(isset($_POST["sy_id"]) && !empty($_POST["sy_id"])){
//Get all section data
$query = $conn->query("SELECT * FROM tbl_curriculum JOIN tbl_grade_level ON tbl_curriculum.grade_level_id = tbl_grade_level.grade_level_id WHERE tbl_curriculum.sy_id = ".$_POST['sy_id']."");
//Count total number of rows
$rowCount = $query->num_rows;
//Display sections list
if($rowCount > 0){
echo '<option value="">Select section</option>';
while($row = $query->fetch_assoc()){
echo '<option value="'.$row['cur_id'].'">'.$row['grade_level_name'].'</option>';
}
}else{
echo '<option value="">Please, assigned section</option>';
}
}
if(isset($_POST["cur_id"]) && !empty($_POST["cur_id"])){
//Get all subject data
$query = $conn->query("SELECT * FROM tbl_curriculum
JOIN tbl_grade_level ON tbl_curriculum.grade_level_id=tbl_grade_level.grade_level_id
JOIN tbl_section ON tbl_curriculum.grade_level_id=tbl_section.grade_level_id
JOIN tbl_subject ON tbl_curriculum.grade_level_id=tbl_subject.grade_level_id
WHERE tbl_curriculum.cur_id = ".$_POST['cur_id']." GROUP BY tbl_subject.subject_id");
//Count total number of rows
$rowCount = $query->num_rows;
//Display subjects list
if($rowCount > 0){
echo '<option value="">Select subject</option>';
while($row = $query->fetch_assoc()){
echo '<option value="'.$row['subject_id'].'" selected>'.$row['subject_name'].'</option>';
}
}else{
echo '<option value="">Subject not offered</option>';
}
}
?>