How to delete duplicate value from drop down list - php

Question

I have the following coding with the values in drop down list and I would like to delete the duplicated value from the list but I don't know how to do??
<select id="dept" name="dept" class="dept" width="100" style="width: 100px">
<?php
while ($line = odbc_fetch_array($result)){
$fullNames=substr($line['fullName'],strpos($line['fullName'],'-')+1);
if ($fullNames==$_POST['dept']){
$selected="selected=\"selected\"";
}
else {
$selected="";
}
echo "<option value=\"".$fullNames."\" $selected>".$fullNames."</option>";
}
?>
</select>
Existing result in $_POST['dept']
AC
HR
AC
Admin
MIS
MIS
Expecting result in $_POST['dept']
AC
Admin
HR
MIS

Answer 1

I have modified your script
<select id="dept" name="dept" class="dept" width="100" style="width: 100px">
<?php
$dropdown = array();
while ($line = odbc_fetch_array($result)){
$fullNames=substr($line['fullName'],strpos($line['fullName'],'-')+1);
$selected="";
if($fullNames==$_POST['dept'])
$selected="selected=\"selected\"";
}
$dropdown[$fullNames] = "<option value=\"".$fullNames."\" $selected>".$fullNames."</option>";
}
echo implode('',$dropdown);
?>
</select>
you can also fetch unique records in your query as you didn't posted query and updatiing your provided code.

Answer 2

Use DISTINCT on your SQL statement to get the unique result.
Example:
SELECT DISTINCT col FROM Table
You can read the details about SQL DISTINCT here : https://www.w3resource.com/sql/select-statement/queries-with-distinct-multiple-columns.php

Answer 3

Since it's in an array you can use
$array = array_unique($array);
this will automatically detect any duplicates and remove them leaving only the first instance in the array, see https://www.php.net/manual/en/function.array-unique.php
EDIT: I'm not 100% sure if I understand how your data is coming in, but if I am understanding it correctly you can try this:
<select id="dept" name="dept" class="dept" width="100" style="width: 100px">
<?php
$fullNames = array();
while ($line = odbc_fetch_array($result)){
$fullNames=substr($line['fullName'],strpos($line['fullName'],'-')+1);
}
$fullNames = array_unique($fullNames);
if ($fullNames==$_POST['dept']){
$selected="selected=\"selected\"";
} else {
$selected="";
}
echo "<option value=\"".$fullNames."\" $selected>".$fullNames."</option>";
}
?>
</select>
That said you probably don't want to be directly using $_POST['dept'] but rather will want to do some validation first on $_POST['dept'] then once you confirm it's a valid value then use it in a variable like this:
$dept = $_POST['dept'];
Then you would need to update the other code to use $dept rather than $_POST['dept']. But this will prevent any unintended consequences from a user submitting an invalid or worse yet a intentionally malformed dept. It is good practice to never trust or directly use user input but always test and validate it.

Answer 4

Maybe you can push names into an array with the current loop then filter out the duplicated values. Then use another loop to echo the tag.
<select id="dept" name="dept" class="dept" width="100" style="width: 100px">
<?php
$array = [];
while ($line = odbc_fetch_array($result)){
$fullNames=substr($line['fullName'],strpos($line['fullName'],'-')+1);
array_push($array,$fullNames);//push all names into a array
}
$array = array_unique($array); //filter the duplicate names.
//another loop to echo the <option>
foreach ($array as $fullNames) {
if ($fullNames==$_POST['dept']){
$selected="selected=\"selected\"";
}
else {
$selected="";
}
echo "<option value=\"".$fullNames."\" $selected>".$fullNames."</option>";
}
?>
</select>