Enabling module on sqlsrv DB driver results in an error

Ok, good luck fixing that :)
(i might look into it another day, but i use mysql, so maybe you want to help)

Here is what the code wants to achieve:
If there are multiple hits, it should just pick the first it can find.
For numeric columnbs I could do a MAX, but for string fields?

Maybe in this case the GROUP BY is not needed at all. Still, some other situations made me paranoid, so I added the GROUP BY to prevent any duplicates.

Any idea?

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For now I'd say we do it with PHP instead of mysql.
Remove the GROUP BY, and instead use PHP to pick the first element in an array.

Btw, this inspired me to explore some crazy way of picking the first element of an associative array.

    $candidates = array(
      'm1' => array(1 => array('m1a', 'm1b'), 3 => array('m1d', 'm1e')),
      'm2' => array(1 => array('m2a', 'm2b'), 3 => array('m2d', 'm2e')),
    );
    foreach ($candidates as $menu_name => &$menu_candidates) {
      ksort($menu_candidates);
      // pick the first array value, two times.
      foreach ($menu_candidates as $menu_candidates) {break;}
      foreach ($menu_candidates as $menu_candidates) {break;}
    }
    dpm($candidates);

Result:

array('m1' => 'm1a', 'm2' => 'm2a')

Crazy nice, isn't it?

Yes, there are other ways to pick the first element of an associative array. If you have some nice suggestion, let me know.
I just read that reset() is not reliable, http://www.php.net/manual/de/function.reset.php#96090

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Now, applying that to menu_CrumbsMultiPlugin_hierarchy::findParent()

  function findParent($path, $item) {
    $q = db_select('menu_links', 'parent');
    $q->innerJoin('menu_links', 'child', 'parent.mlid = child.plid');
    $q->addExpression('parent.link_path', 'parent_path');
    $q->addExpression('parent.menu_name', 'menu_name');
    $q->addExpression('parent.depth', 'depth');
    $q->condition('child.link_path', $path);
    // If we'd use both GROUP BY and parent.link_path, sqlsrv would complain,
    // because it would not know which row's link path to return in case of
    // duplicate.
    // There is no useful aggregate function for strings, unfortunately.
    // $q->groupBy('parent.menu_name');
    $candidates = array();
    foreach ($q->execute() as $row) {
      $candidates[$row->menu_name][$row->depth][] = $row->parent_path;
    }
    foreach ($candidates as &$menu_candidates) {
      ksort($menu_candidates);
      // pick the first array value, two times.
      // $menu_candidates is already a reference, so here we use it without '&'.
      foreach ($menu_candidates as $menu_candidates) break;
      foreach ($menu_candidates as $menu_candidates) break;
    }
    return $candidates;
  }

Anyone willing to test this?
(not in patch mood today)

This should be fixed now.

The "solution" here is ugly and awkward.
Let's do something equivalent to #1788214-4: Crumbs compatibility issue with PostgreSQL instead.

Here is a patch to make this look nicer.

Looks good.

The awkward code is history :)