diff --git a/includes/controller/shifts_controller.php b/includes/controller/shifts_controller.php
index 0d36aa49..aa1ac5d9 100644
--- a/includes/controller/shifts_controller.php
+++ b/includes/controller/shifts_controller.php
@@ -31,51 +31,16 @@ function shift_edit_controller() {
   }
   $shift_id = $_REQUEST['edit_shift'];
   
-  // Locations laden
-  $rooms = sql_select("SELECT * FROM `Room` WHERE `show`='Y' ORDER BY `Name`");
-  $room_array = [];
-  foreach ($rooms as $room) {
-    $room_array[$room['RID']] = $room['Name'];
-  }
+  $shift = Shift($shift_id);
   
-  $shift = sql_select("
-        SELECT `ShiftTypes`.`name`, `Shifts`.*, `Room`.* FROM `Shifts`
-        JOIN `Room` ON (`Shifts`.`RID` = `Room`.`RID`)
-        JOIN `ShiftTypes` ON (`ShiftTypes`.`id` = `Shifts`.`shifttype_id`)
-        WHERE `SID`='" . sql_escape($shift_id) . "'");
-  if (count($shift) == 0) {
-    redirect(page_link_to('user_shifts'));
-  }
-  $shift = $shift[0];
+  $room = select_array(Rooms(), 'RID', 'Name');
+  $angeltypes = select_array(AngelTypes(), 'id', 'name');
+  $shifttypes = select_array(ShiftTypes(), 'id', 'name');
   
-  // Engeltypen laden
-  $types = sql_select("SELECT * FROM `AngelTypes` ORDER BY `name`");
-  $angel_types = [];
-  $needed_angel_types = [];
-  foreach ($types as $type) {
-    $angel_types[$type['id']] = $type;
-    $needed_angel_types[$type['id']] = 0;
-  }
-  
-  $shifttypes_source = ShiftTypes();
-  $shifttypes = [];
-  foreach ($shifttypes_source as $shifttype) {
-    $shifttypes[$shifttype['id']] = $shifttype['name'];
-  }
-  
-  // Benötigte Engeltypen vom Raum
-  $needed_angel_types_source = sql_select("SELECT `AngelTypes`.*, `NeededAngelTypes`.`count` FROM `AngelTypes` LEFT JOIN `NeededAngelTypes` ON (`NeededAngelTypes`.`angel_type_id` = `AngelTypes`.`id` AND `NeededAngelTypes`.`room_id`='" . sql_escape($shift['RID']) . "') ORDER BY `AngelTypes`.`name`");
-  foreach ($needed_angel_types_source as $type) {
-    if ($type['count'] != "") {
-      $needed_angel_types[$type['id']] = $type['count'];
-    }
-  }
-  
-  // Benötigte Engeltypen von der Schicht
-  $needed_angel_types_source = sql_select("SELECT `AngelTypes`.*, `NeededAngelTypes`.`count` FROM `AngelTypes` LEFT JOIN `NeededAngelTypes` ON (`NeededAngelTypes`.`angel_type_id` = `AngelTypes`.`id` AND `NeededAngelTypes`.`shift_id`='" . sql_escape($shift_id) . "') ORDER BY `AngelTypes`.`name`");
-  foreach ($needed_angel_types_source as $type) {
-    if ($type['count'] != "") {
-      $needed_angel_types[$type['id']] = $type['count'];
+  $needed_angel_types = select_array(NeededAngelTypes_by_shift($shift_id), 'id', 'count');
+  foreach (array_keys($angeltypes) as $angeltype_id) {
+    if (! isset($needed_angel_types[$angeltype_id])) {
+      $needed_angel_types[$angeltype_id] = 0;
     }
   }
   
@@ -90,11 +55,10 @@ function shift_edit_controller() {
     $title = strip_request_item('title');
     
     // Auswahl der sichtbaren Locations für die Schichten
-    if (isset($_REQUEST['rid']) && preg_match("/^[0-9]+$/", $_REQUEST['rid']) && isset($room_array[$_REQUEST['rid']])) {
+    if (isset($_REQUEST['rid']) && preg_match("/^[0-9]+$/", $_REQUEST['rid']) && isset($room[$_REQUEST['rid']])) {
       $rid = $_REQUEST['rid'];
     } else {
       $valid = false;
-      $rid = $rooms[0]['RID'];
       $msg .= error(_("Please select a room."), true);
     }
     
@@ -144,11 +108,11 @@ function shift_edit_controller() {
       if ($result === false) {
         engelsystem_error('Unable to update shift.');
       }
-      sql_query("DELETE FROM `NeededAngelTypes` WHERE `shift_id`='" . sql_escape($shift_id) . "'");
+      NeededAngelTypes_delete_by_shift($shift_id);
       $needed_angel_types_info = [];
       foreach ($needed_angel_types as $type_id => $count) {
-        sql_query("INSERT INTO `NeededAngelTypes` SET `shift_id`='" . sql_escape($shift_id) . "', `angel_type_id`='" . sql_escape($type_id) . "', `count`='" . sql_escape($count) . "'");
-        $needed_angel_types_info[] = $angel_types[$type_id]['name'] . ": " . $count;
+        NeededAngelType_add($shift_id, $type_id, null, $count);
+        $needed_angel_types_info[] = $angeltypes[$type_id] . ": " . $count;
       }
       
       engelsystem_log("Updated shift '" . $shifttypes[$shifttype_id] . ", " . $title . "' from " . date("Y-m-d H:i", $start) . " to " . date("Y-m-d H:i", $end) . " with angel types " . join(", ", $needed_angel_types_info));
@@ -160,9 +124,9 @@ function shift_edit_controller() {
     }
   }
   
-  $angel_types = "";
-  foreach ($types as $type) {
-    $angel_types .= form_spinner('type_' . $type['id'], $type['name'], $needed_angel_types[$type['id']]);
+  $angel_types_spinner = "";
+  foreach ($angeltypes as $angeltype_id => $angeltype_name) {
+    $angel_types_spinner .= form_spinner('type_' . $angeltype_id, $angeltype_name, $needed_angel_types[$angeltype_id]);
   }
   
   return page_with_title(shifts_title(), [
@@ -171,11 +135,11 @@ function shift_edit_controller() {
       form([
           form_select('shifttype_id', _('Shifttype'), $shifttypes, $shifttype_id),
           form_text('title', _("Title"), $title),
-          form_select('rid', _("Room:"), $room_array, $rid),
+          form_select('rid', _("Room:"), $room, $rid),
           form_text('start', _("Start:"), date("Y-m-d H:i", $start)),
           form_text('end', _("End:"), date("Y-m-d H:i", $end)),
           '<h2>' . _("Needed angels") . '</h2>',
-          $angel_types,
+          $angel_types_spinner,
           form_submit('submit', _("Save")) 
       ]) 
   ]);
diff --git a/includes/model/NeededAngelTypes_model.php b/includes/model/NeededAngelTypes_model.php
index 96ceca83..77a23c3d 100644
--- a/includes/model/NeededAngelTypes_model.php
+++ b/includes/model/NeededAngelTypes_model.php
@@ -1,9 +1,59 @@
 <?php
 
+/**
+ * Entity needed angeltypes describes how many angels of given type are needed for a shift or in a room.
+ */
+
+/**
+ * Insert a new needed angel type.
+ *
+ * @param int $shift_id
+ *          The shift. Can be null, but then a room_id must be given.
+ * @param int $angeltype_id
+ *          The angeltype
+ * @param int $room_id
+ *          The room. Can be null, but then a shift_id must be given.
+ * @param int $count
+ *          How many angels are needed?
+ */
+function NeededAngelType_add($shift_id, $angeltype_id, $room_id, $count) {
+  $result = sql_query("
+      INSERT INTO `NeededAngelTypes` SET 
+      `shift_id`=" . sql_null($shift_id) . ", 
+      `angel_type_id`='" . sql_escape($angeltype_id) . "', 
+      `room_id`=" . sql_null($room_id) . ",
+      `count`='" . sql_escape($count) . "'");
+  if ($result === false) {
+    return false;
+  }
+  return sql_id();
+}
+
+/**
+ * Deletes all needed angel types from given shift.
+ *
+ * @param int $shift_id
+ *          id of the shift
+ */
+function NeededAngelTypes_delete_by_shift($shift_id) {
+  return sql_query("DELETE FROM `NeededAngelTypes` WHERE `shift_id`='" . sql_escape($shift_id) . "'");
+}
+
+/**
+ * Deletes all needed angel types from given room.
+ *
+ * @param int $room_id
+ *          id of the room
+ */
+function NeededAngelTypes_delete_by_room($room_id) {
+  return sql_query("DELETE FROM `NeededAngelTypes` WHERE `room_id`='" . sql_escape($room_id) . "'");
+}
+
 /**
  * Returns all needed angeltypes and already taken needs.
  *
- * @param shiftID id of shift
+ * @param int $shiftID
+ *          id of shift
  */
 function NeededAngelTypes_by_shift($shiftId) {
   $needed_angeltypes_source = sql_select("
diff --git a/includes/model/Room_model.php b/includes/model/Room_model.php
index 4d03260a..6b6e269e 100644
--- a/includes/model/Room_model.php
+++ b/includes/model/Room_model.php
@@ -1,8 +1,17 @@
 <?php
 
+/**
+ * returns a list of rooms.
+ * @param boolean $show_all returns also hidden rooms when true
+ */
+function Rooms($show_all = false) {
+  return sql_select("SELECT * FROM `Room`" . ($show_all ? "" : " WHERE `show`='Y'") . " ORDER BY `Name`");
+}
+
 /**
  * Delete a room
- * @param int $room_id
+ *
+ * @param int $room_id          
  */
 function Room_delete($room_id) {
   return sql_query("DELETE FROM `Room` WHERE `RID`=" . sql_escape($room_id));
diff --git a/includes/pages/admin_rooms.php b/includes/pages/admin_rooms.php
index d34d4386..7641eb18 100644
--- a/includes/pages/admin_rooms.php
+++ b/includes/pages/admin_rooms.php
@@ -36,20 +36,24 @@ function admin_rooms() {
     }
     
     if (test_request_int('id')) {
-      $room = sql_select("SELECT * FROM `Room` WHERE `RID`='" . sql_escape($_REQUEST['id']) . "'");
-      if (count($room) > 0) {
-        $room_id = $_REQUEST['id'];
-        $name = $room[0]['Name'];
-        $from_pentabarf = $room[0]['FromPentabarf'];
-        $public = $room[0]['show'];
-        $number = $room[0]['Number'];
-        $needed_angeltypes = sql_select("SELECT * FROM `NeededAngelTypes` WHERE `room_id`='" . sql_escape($room_id) . "'");
-        foreach ($needed_angeltypes as $needed_angeltype) {
-          $angeltypes_count[$needed_angeltype['angel_type_id']] = $needed_angeltype['count'];
-        }
-      } else {
+      $room = Room($_REQUEST['id']);
+      if ($room === false) {
+        engelsystem_error("Unable to load room.");
+      }
+      if ($room == null) {
         redirect(page_link_to('admin_rooms'));
       }
+      
+      $room_id = $_REQUEST['id'];
+      $name = $room['Name'];
+      $from_pentabarf = $room['FromPentabarf'];
+      $public = $room['show'];
+      $number = $room['Number'];
+      
+      $needed_angeltypes = sql_select("SELECT * FROM `NeededAngelTypes` WHERE `room_id`='" . sql_escape($room_id) . "'");
+      foreach ($needed_angeltypes as $needed_angeltype) {
+        $angeltypes_count[$needed_angeltype['angel_type_id']] = $needed_angeltype['count'];
+      }
     }
     
     if ($_REQUEST['show'] == 'edit') {
@@ -106,7 +110,7 @@ function admin_rooms() {
             engelsystem_log("Room created: " . $name . ", pentabarf import: " . $from_pentabarf . ", public: " . $public . ", number: " . $number);
           }
           
-          sql_query("DELETE FROM `NeededAngelTypes` WHERE `room_id`='" . sql_escape($room_id) . "'");
+          NeededAngelTypes_delete_by_room($room_id);
           $needed_angeltype_info = [];
           foreach ($angeltypes_count as $angeltype_id => $angeltype_count) {
             $angeltype = AngelType($angeltype_id);
@@ -114,7 +118,7 @@ function admin_rooms() {
               engelsystem_error("Unable to load angeltype.");
             }
             if ($angeltype != null) {
-              sql_query("INSERT INTO `NeededAngelTypes` SET `room_id`='" . sql_escape($room_id) . "', `angel_type_id`='" . sql_escape($angeltype_id) . "', `count`='" . sql_escape($angeltype_count) . "'");
+              NeededAngelType_add(null, $angeltype_id, $room_id, $count);
               $needed_angeltype_info[] = $angeltype['name'] . ": " . $angeltype_count;
             }
           }
diff --git a/includes/sys_page.php b/includes/sys_page.php
index 27e3e8ba..e62909ab 100644
--- a/includes/sys_page.php
+++ b/includes/sys_page.php
@@ -18,6 +18,24 @@ function raw_output($output) {
   die();
 }
 
+/**
+ * Helper function for transforming list of entities into array for select boxes.
+ * 
+ * @param array $data
+ *          The data array
+ * @param string $key_name
+ *          name of the column to use as id/key
+ * @param string $value_name
+ *          name of the column to use as displayed value
+ */
+function select_array($data, $key_name, $value_name) {
+  $ret = [];
+  foreach ($data as $value) {
+    $ret[$value[$key_name]] = $value[$value_name];
+  }
+  return $ret;
+}
+
 /**
  * Returns an int[] from given request param name.
  *