将SQL /文件结构数据下载到iPad应用程序的最有效方法是什么？

Question

Currently i have:

A server that has mySQL installed and accessed by PHP scripts. All data is in SQL database including photos.

What i want to do is move the photos out the database and into their own file structure (that bit i can do) what i don't know is how to get all the string data out the database and photos into one return message, potentially I'm talking a fe hundred rows of data.

Currently i perform sql query and have to do the following

while($row = mysql_fetch_array($result))
    {
        $encodepic = base64_encode($row['IMAGE']);
        $posts[] = array($row['ID'],$row['COL1'], $row['COL2'], $row['COL3'], $row['COL4'], $encodepic, $row['COL5'], $row['COL6'], $row['COL7']);
    }
    echo json_encode($posts);

If i change the $row['IMAGE'] for the file (obviously read it first, won't that make system really slow?

Is there a better way full stop of doing what I'm trying to do

Also for code tidiness i want to send the dictionary down so other end (unless this makes system inefficient)

Thanks