drupal how to get fetch multple rows

Question

how to fetch multiple rows in drupal and store the desired row in variable .

while ($fields = db_fetch_array($result)) { echo ""; foreach($fields as $key => $value) { echo "$key = $value\n"; }

it works it displays the results but i want to get the value of one row and store in another varaible like $fields['some column name '] how to do that....