如何在下拉列表中回显先前选择的选项？

Question

I am using the follow bit below. I am first querying the db to see all available options but this is for an edit form so i want the drop down to show the previously selected value so i did another query and got the selection. When i do it the way i have it below it will keep repeating the previously selected selection after each available option. HOw to fix this?

<option>Select Sales rep</option>
<?php

$query="select agent_id, agent_name from agent_names where agent_id='$ad' 
order by agent_name asc";
$result=mysql_query($query);
while(list($agent_id, $agent_name)=mysql_fetch_row($result)) {
    echo "<option value=\"".$previousname."\">".$previousselection."</option>
    <option value=\"".$agent_id."\">".$agent_name."</option>";
}


?>

Answer 1

Just check if $agent_id equals $previousname (perhaps you mean $previousid?) and echo selected="selected" if so:

while(list($agent_id, $agent_name)=mysql_fetch_row($result)) {
    $selected = $agent_id == $previousname;
    echo "<option " . ($selected ? "selected=\"selected\"" : "") . " value=\"".$agent_id."\">".$agent_name."</option>";
}

Another option is to output the previous selected item before your while loop, and exclude it in your sql query.