Question

I am trying to check my database and return any new additions to the DB.

My client can pass in the ID of the last item it received from the DB. So i think that would be a good starting place.

So is it the case that I set the offset to the ID(theid) i pass in as an argument to the php script and that will only return Database entries newer than that id? Or am i barking up the wrong tree altogether?

Here is what I mean with code

$theid  = isset($_GET['theid']) ? $_GET['theid'] : "";
$type   = isset($_GET['type']) ? $_GET['type'] : "global";
$offset = isset($_GET['offset']) ? $_GET['offset'] : theid;
$count  = isset($_GET['count']) ? $_GET['count'] : "100";
$sort   = isset($_GET['sort']) ? $_GET['sort'] : "id ASC";

// Localize the GET variables
$udid  = isset($_GET['udid']) ? $_GET['udid'] : "";
$name  = isset($_GET['name']) ? $_GET['name']  : "";
$clubname  = isset($_GET['clubname']) ? $_GET['clubname']  : "";

// Protect against sql injections
$type   = mysql_real_escape_string($type);
$offset = mysql_real_escape_string($offset);
$count  = mysql_real_escape_string($count);
$sort   = mysql_real_escape_string($sort);
$udid   = mysql_real_escape_string($udid);
$name   = mysql_real_escape_string($name);
$clubname   = mysql_real_escape_string($clubname);

// Build the sql query
$sql = "SELECT * FROM $table WHERE ";

switch($type) {
    case "global":
        $sql .= "1 ";
        break;
    case "device":
        $sql .= "udid = '$udid' ";
        break;
    case "name":
        $sql .= "name = '$name' ";
        break;
    case "clubname":
        $sql .= "clubname = '$clubname' ";
        break;
}

$sql .= "ORDER BY $sort ";
$sql .= "LIMIT $offset,$count ";

$result = mysql_query($sql,$conn);

if(!$result) {
    die("Error retrieving scores " . mysql_error());
}

Many Thanks,
-Code

Answer 1

Assuming that the ID is a sequenced number, and newer entries will ALWAYS have a higher ID than the previous, you want the following:

SELECT * FROM table WHERE id > $id;

Otherwise, you need to add a timestamp to your tables, and run two queries:

SELECT createdAt FROM table WHERE id = $id;

Assign that value to $timestamp and then run the following:

SELECT * FROM table WHERE createdAt > $timestamp

Optionally, you could combine the queries:

SELECT * FROM table WHERE createdAt > (SELECT createdAt FROM table WHERE id = $id)

Using the offset is a bad idea. If any records prior to your ID are deleted, your results will be inaccurate. For example, lets say the following happens:

• Insert 100 records (last ID is 100)
• Delete records 47 and 48
• Add 1 record ( last ID is 101 )
• Find records new since id #100

If you use an offset of 100, you will have no records returned.