diff --git a/Admin/Install/db.json b/Admin/Install/db.json
index 5e5bc1f..54b34d1 100644
--- a/Admin/Install/db.json
+++ b/Admin/Install/db.json
@@ -12,7 +12,8 @@
             "clientmgmt_client_no": {
                 "name": "clientmgmt_client_no",
                 "type": "VARCHAR(255)",
-                "null": false
+                "null": false,
+                "unique": true
             },
             "clientmgmt_client_no_reverse": {
                 "name": "clientmgmt_client_no_reverse",
@@ -39,8 +40,8 @@
                 "type": "DATETIME",
                 "null": false
             },
-            "clientmgmt_client_account": {
-                "name": "clientmgmt_client_account",
+            "clientmgmt_client_profile": {
+                "name": "clientmgmt_client_profile",
                 "type": "INT",
                 "null": false,
                 "foreignTable": "profile_account",
diff --git a/Controller/BackendController.php b/Controller/BackendController.php
index 91b852f..439e677 100644
--- a/Controller/BackendController.php
+++ b/Controller/BackendController.php
@@ -49,7 +49,7 @@ final class BackendController extends Controller
         $view->setTemplate('/Modules/ClientManagement/Theme/Backend/clients-list');
         $view->addData('nav', $this->app->moduleManager->get('Navigation')->createNavigationMid(1003102001, $request, $response));
 
-        $client = ClientMapper::getNewest(50);
+        $client = ClientMapper::getAll();
         $view->addData('client', $client);
 
         return $view;
diff --git a/Models/Client.php b/Models/Client.php
index 090b35d..c0568a3 100644
--- a/Models/Client.php
+++ b/Models/Client.php
@@ -43,7 +43,7 @@ class Client
 
     private \DateTime $createdAt;
 
-    private $profile = null;
+    private Profile $profile;
 
     private array $files = [];
 
diff --git a/Models/ClientMapper.php b/Models/ClientMapper.php
index 124f500..e329b1f 100644
--- a/Models/ClientMapper.php
+++ b/Models/ClientMapper.php
@@ -43,7 +43,7 @@ final class ClientMapper extends DataMapperAbstract
         'clientmgmt_client_type'       => ['name' => 'clientmgmt_client_type',       'type' => 'int',      'internal' => 'type'],
         'clientmgmt_client_info'       => ['name' => 'clientmgmt_client_info',       'type' => 'string',   'internal' => 'info'],
         'clientmgmt_client_created_at' => ['name' => 'clientmgmt_client_created_at', 'type' => 'DateTime', 'internal' => 'createdAt', 'readonly' => true],
-        'clientmgmt_client_account'    => ['name' => 'clientmgmt_client_account',    'type' => 'int',      'internal' => 'profile'],
+        'clientmgmt_client_profile'    => ['name' => 'clientmgmt_client_profile',    'type' => 'int',      'internal' => 'profile'],
     ];
 
     /**
@@ -79,7 +79,7 @@ final class ClientMapper extends DataMapperAbstract
     protected static array $ownsOne = [
         'profile' => [
             'mapper' => ProfileMapper::class,
-            'self'   => 'clientmgmt_client_account',
+            'self'   => 'clientmgmt_client_profile',
         ],
     ];
 
diff --git a/Theme/Backend/clients-profile.tpl.php b/Theme/Backend/clients-profile.tpl.php
index 2bbbc22..aabb893 100644
--- a/Theme/Backend/clients-profile.tpl.php
+++ b/Theme/Backend/clients-profile.tpl.php
@@ -75,7 +75,9 @@ echo $this->getData('nav')->render();
                     </section>
 
                     <section class="portlet highlight-4">
-                        <div class="portlet-body"></div>
+                        <div class="portlet-body">
+                            <textarea class="undecorated"></textarea>
+                        </div>
                     </section>
 
                     <section class="portlet">
diff --git a/tests/Models/ClientMapperTest.php b/tests/Models/ClientMapperTest.php
index e69de29..c73805e 100644
--- a/tests/Models/ClientMapperTest.php
+++ b/tests/Models/ClientMapperTest.php
@@ -0,0 +1,70 @@
+<?php
+/**
+ * Orange Management
+ *
+ * PHP Version 7.4
+ *
+ * @package   tests
+ * @copyright Dennis Eichhorn
+ * @license   OMS License 1.0
+ * @version   1.0.0
+ * @link      https://orange-management.org
+ */
+declare(strict_types=1);
+
+namespace Modules\ClientManagement\tests\Models;
+
+use Modules\Admin\Models\NullAccount;
+use Modules\ClientManagement\Models\Client;
+use Modules\ClientManagement\Models\ClientMapper;
+use Modules\Profile\Models\NullProfile;
+use Modules\Profile\Models\ProfileMapper;
+use Modules\Profile\Models\Profile;
+
+/**
+ * @internal
+ */
+class ClientMapperTest extends \PHPUnit\Framework\TestCase
+{
+    public function testCR() : void
+    {
+        $client = new Client();
+        $client->setNumber('123456789');
+
+        // This is required because by default a NullAccount without an ID is created in the Profile model
+        // but NullModels without ids are handled like "null" values which are not allowed for Accounts.
+        $profile = ProfileMapper::getFor(1, 'account');
+        $profile = $profile instanceof NullProfile ? new Profile() : $profile;
+        if ($profile->getAccount()->getId() === 0) {
+            $profile->setAccount(new NullAccount(1));
+        }
+
+        $client->setProfile($profile);
+
+        $id = ClientMapper::create($client);
+        self::assertGreaterThan(0, $client->getId());
+        self::assertEquals($id, $client->getId());
+    }
+
+    /**
+     * @group volume
+     * @group module
+     * @coversNothing
+     */
+    public function testClientVolume() : void
+    {
+        $profile = ProfileMapper::getFor(1, 'account');
+        $profile = $profile instanceof NullProfile ? new Profile() : $profile;
+        if ($profile->getAccount()->getId() === 0) {
+            $profile->setAccount(new NullAccount(1));
+        }
+
+        for ($i = 0; $i < 100; ++$i) {
+            $client = new Client();
+            $client->setNumber((string) \mt_rand(100000, 999999));
+
+            $client->setProfile($profile);
+            ClientMapper::create($client);
+        }
+    }
+}