从php的同一文件中的下拉列表中获取选定选项的值? [英] Get the value of selected option from a dropdown list in the same file in php?

问题描述

我有2个下拉列表，一个是大学，另一个是分支，所以我想做的是，每当用户从第一个下拉列表中选择一个大学时，脚本应自动检查该分支中的可用分支大学，应该将它们添加到第二个下拉列表(即分支机构)中，目前我是手动执行的.

I have 2 drop down list, one is college and other is branch, so what i want to do is that whenever a user selects a college from the first drop down list, the script should automatically check for the branches available in that college and should add them to the second drop down list i.e. of branches, currently I am doing it manually.

<?php
mysql_connect("localhost", "root", "") or die("Connection Failed");
mysql_select_db("pet")or die("Connection Failed");
$query = "SELECT distinct insti_name FROM maininfo";
$result = mysql_query($query);




$query2 = "SELECT distinct insti_name FROM maininfo";
$result2 = mysql_query($query2);

?>
<form name="myform" id="one" method="post" action="compare.php">
Select first college: 
<select name="coll1">
<?php
while ($line = mysql_fetch_array($result, MYSQL_ASSOC)) {
?>
<option value="<?php echo $line['insti_name'];?>"> <?php echo $line['insti_name'];?>
</option>

<?php
}
?>
</select>
<br /><p>Select the branch:


<select name="brn1">

<option value="0" selected>(please select:)</option>
<option value="ce">Civil</option>
<option value="cse">Computer Science Engineering</option>
<option value="ec">Electronics and Communication</option>
<option value="it">Information Technology</option>
<option value="aeie">AEIE</option>
<option value="mech">Mechanical</option>
<option value="elect elex">Elect Elex</option>
<option value="ee">Electricals</option>
<option value="el">EL</option>
<option value="chem">Chemical</option>
<option value="fire">Fire</option>
<option value="ei">ei</option>
<option value="food">Food</option>
<option value="ip">Information Practises</option>
<option value="bt">Bio Technology</option>

</select>


<br>
<hr width=100% height=4>

Select second college: 
<select name="coll2">
<?php
while ($line = mysql_fetch_array($result2, MYSQL_ASSOC)) {
?>
<option value="<?php echo $line['insti_name'];?>"> <?php echo $line['insti_name'];?>
</option>

<?php
}
?>


</select>


<br /><p>Select the branch:
<select name="brn2">
<option value="0" selected>(please select:)</option>
<option value="ce">Civil</option>
<option value="cse">Computer Science Engineering</option>
<option value="ec">Electronics and Communication</option>
<option value="it">Information Technology</option>
<option value="aeie">AEIE</option>
<option value="mech">Mechanical</option>
<option value="elect elex">Elect Elex</option>
<option value="ee">Electricals</option>
<option value="el">EL</option>
<option value="chem">Chemical</option>
<option value="fire">Fire</option>
<option value="ei">ei</option>
<option value="food">Food</option>
<option value="ip">Information Practises</option>
<option value="bt">Bio Technology</option>

</select>
<br><br>
<input type="submit" name="Submit" value="Compare Colleges" >
</form>

推荐答案

请注意，如果使用AJAX，这是更好的用户体验.但是，您需要将表单设置为在大学选择框更改时提交.然后，在您的PHP中，您需要执行以下操作:

As a note, this is a better user-experience if done with AJAX. However, you need to set your form to submit onchange of your college select box. Then, in your PHP, you need to do:

if( isset( $_POST['coll1'] ) ) {
    //query your branches and populate select same as you did for colleges.
    //e.g. "SELECT * FROM Branches WHERE CollegeId=".mysql_real_escape_string($_POST['coll1']);
}

是否有足够的信息供您使用?

Is that enough info for you to work from?

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