Query MySQL alphanumeric w/ Limit using MeekroDB

I'm trying to sort by certain alphanumeric range 1-3 & A-B for first 15 matches, but am getting nothing in output. Using MeekroDB. Not sure how to translate what I have here to their method.

$results = DB::query("SELECT substr(theme, 1, 1) as Alphabet
FROM gallery ORDER BY (CASE theme
  WHEN '1%' THEN 1
  WHEN '2%' THEN 2
  WHEN '3%' THEN 3
  WHEN 'A%' THEN 4
  WHEN 'B%' THEN 5
  ELSE -1
END) LIMIT 15"); 

$x = 0
foreach ($results as $row) {
  $x++;
  if ($x == 1) {  // first in query
    $t1 = $row['theme'];
    $d1 = $row['developer'];
    $th1 = $row['thumb'];
    $thlg1 = $row['thumb_lg'];
  }
  ...
}

Echo example in body:

<img src="<?php echo($th1); ?>" data-retina="<?php echo($thlg1); ?>" alt="<?php echo($t1); ?>" />
<span><p class="hname"><?php echo($t1); ?></p>
<p class="hdev"><?php echo($d1); ?></p></span>

Update2:

$results = DB::query("SELECT substr(theme, 1, 1) as Alphabet, theme, developer, thumb, thumb_lg
FROM gallery ORDER BY (CASE
  WHEN theme LIKE '1%' THEN 1
  WHEN theme LIKE '2%' THEN 2
  WHEN theme LIKE '3%' THEN 3
  WHEN theme LIKE 'A%' THEN 4
  WHEN theme LIKE 'B%' THEN 5
  ELSE -1
END) LIMIT 15");

Update3:

$results = DB::query("SELECT substr(theme, 1, 1) as Alphabet, theme, developer, thumb, thumb_lg FROM gallery
  ORDER BY (CASE Alphabet
    WHEN '1' THEN 1
    WHEN '2' THEN 2
    WHEN '3' THEN 3  
    WHEN 'A' THEN 4
    WHEN 'B' THEN 5
    ELSE 6
  END)
  LIMIT 15");

The ORDER BY clause should be:

ORDER BY CASE Alphabet
    WHEN '1' THEN 1
    WHEN '2' THEN 2
    WHEN '3' THEN 3
    WHEN 'A' THEN 4
    WHEN 'B' THEN 5
    ELSE 6
END, theme

Your code is doing exact matches on the whole theme, '1%' should have been matched using LIKE. My version just uses the first character, which you already extracted into Alphabet.

Another way to write this is:

ORDER BY IF(LOCATE(Alphabet, "123AB"), 0, 1), theme

This works because the order of your first characters matches the normal lexicographic order.