我应该在函数内返回DB结果还是循环遍历函数外的结果？

Question

So I was wondering what's the best way/practise of querying the database in a function and then printing the results back to the .php page. I got taught to do the query in the function(), call the function() inside the .php page and then loop through the resultset inside the .php page.

Here is an example of what i'm doing now - Im wondering if this is "Unsafe" or "Not secure" or slower than returning the results in the function? Because at the moment - This is taking a while to load on the page? Could this be because I'm doing using if statements inside the while loop?

     showPlaylist($staticTestUser);


    if($numRecords == 0){
            echo "<div class='no-found'>No playlists found</div>";
        }
        else{
                $htmloutput = "<div class='playlist-wrap'>";

            $i = 1;
            while($arrRows = $stmt->fetch(PDO::FETCH_ASSOC)){
                    $title = $arrRows['song-title']
                    $thumbnail=$arrRows['thumb']

                    $playTitle = $arrRows['playlistName'];
                    $htmloutput .= "<div class='playlist-head'>";
                    //Make sure the title is only shown once - Loop through the rest.
                    if($i == 1){
                        $htmloutput .= $playTitle;
                    }

                    $htmloutput .= "</div>";
                    $htmloutput .= "<div class='playlist-item'>";
                        $htmloutput .= "<div class='play-thumb'>".$thumbnail."</div>";
                        $htmloutput .= "<div class='play-title'>".substr($title, 0,30)."...</div>";
                    $htmloutput .= "</div>";

                    if($i == $numRecords){
                    $playId = $arrRows['pID'];
                    $htmloutput .= "<div class='playlist-footer'>";
                        $htmloutput .= "<div class='play-stats'>";
                        $htmloutput .= "Likes:".$arrRows['likes']." -- Dislikes: ".$arrRows['dislikes'];
                        $htmloutput .= "</div>";
                        $htmloutput .= "<div class='play-vote'>";
                        $htmloutput .= "<button name='playLike' type='submit' value='$playId'>Like</button>";
                        $htmloutput .= "<button name='playDislike' type='submit' value='$playId'>Dislike</button>"; 
                        $htmloutput .= "</div>";
                    $htmloutput .= "</div>";
                }
                $i++;
                    unset($playTitle);
            }
            $htmloutput .= "</div>";

                echo $htmloutput;
        }

Answer 1

There aren't any specific security issues with your code that I can see, but best practice right now is to use the MVC - model, view, controller - design pattern. See here. Or the MVP - model, view, presenter - design pattern. See here. Both are very similar.

Using one of these patterns has many benefits but the biggest ones in my opinion are code readable, portability, and reusability. It may also speed things up as well.

The if statements inside your code wouldn't be whats slowing your code down - it would probably be the repeated fetch at the beginning of the while loop.