How would one script for a dynamic list to keep selected item in list

[drranch]

I have a dynamic list that once an item is selected the form retrieves the data from the database, but when the form is refreshed the list defaults back to the defaulted item specified in the script.

Is there a way to have the list stay on the item selected rather than defaulting to the specified default in the script?

Here is my dynamic list script:
<SELECT name="cars" size="1" onchange=cars.submit()>
    <option >Select a car</option>
    <?php
do { 
?>
    <option value="<?php echo $row_rcars['cars']?>"><?php echo $row_cars['car']?></option>
    <?php
} while ($row_cars= mysql_fetch_assoc($rscars));
  $rows = mysql_num_rows($rscars);
  if($rows > 0) {
      mysql_data_seek($rscars, 0);
  $row_rcars = mysql_fetch_assoc($rscars);
  }
?>
  </select>

[Barand]

Compare each option's value with the current value. If they are the same, put "selected" inside the option tag
[code]
<option value='1' > abc </option>
<option value='2'  selected> xyz </option>
<option value='3' > mno </option>
[/code]
"xyz" will display in the dropdown

[drranch]

Ok  this works - added code in red.  So Barand's suggestion makes sense in comparing the selected with the value of the selected... It works great but my select list has a blank field as a select option ???

<SELECT name="cars" size="1" onchange=cars.submit()>
    <option >Select a car</option>
    <?php
do { 
?>
    <option value="<?php echo $row_rcars['cars']?>[color=red]<?php if ($cars == $row_rcars['cars']) echo "SELECTED"; ?>[/color]"><?php echo $row_cars['car']?></option>
    <?php
} while ($row_cars= mysql_fetch_assoc($rscars));
  $rows = mysql_num_rows($rscars);
  if($rows > 0) {
      mysql_data_seek($rscars, 0);
     $row_rcars = mysql_fetch_assoc($rscars);
  }
?>
  </select>