diff --git a/classes/form/rights_config_filter_form.php b/classes/form/rights_config_filter_form.php
index 4920627..05164d1 100644
--- a/classes/form/rights_config_filter_form.php
+++ b/classes/form/rights_config_filter_form.php
@@ -27,15 +27,6 @@
 
 namespace local_ai_manager\form;
 
-use core_plugin_manager;
-use local_ai_manager\base_connector;
-use local_ai_manager\base_purpose;
-use local_ai_manager\local\tenant;
-use local_ai_manager\local\userinfo;
-use local_ai_manager\manager;
-use local_bycsauth\idmgroup;
-use local_bycsauth\school;
-
 defined('MOODLE_INTERNAL') || die;
 
 global $CFG;
diff --git a/classes/hook/userinfo_extend.php b/classes/hook/userinfo_extend.php
index af884d1..ebf6205 100644
--- a/classes/hook/userinfo_extend.php
+++ b/classes/hook/userinfo_extend.php
@@ -16,7 +16,7 @@
 
 namespace local_ai_manager\hook;
 
-use core\exception\coding_exception;
+use coding_exception;
 use local_ai_manager\local\userinfo;
 
 /**
diff --git a/classes/local/rights_config_table.php b/classes/local/rights_config_table.php
index 7d99fe3..d503f35 100644
--- a/classes/local/rights_config_table.php
+++ b/classes/local/rights_config_table.php
@@ -72,7 +72,7 @@ public function __construct(
         $from =
                 '{user} u LEFT JOIN {local_ai_manager_userinfo} ui ON u.id = ui.userid';
         $where = 'u.deleted != 1 AND u.suspended != 1 AND ' . $tenantfield . ' = :tenant';
-        $params = ['tenant' => $tenant->get_identifier()];
+        $params = ['tenant' => $tenant->get_sql_identifier()];
 
         $usertableextend = new usertable_extend($tenant, $columns, $headers, $filterids, $fields, $from, $where, $params);
         \core\di::get(\core\hook\manager::class)->dispatch($usertableextend);
@@ -86,7 +86,7 @@ public function __construct(
 
         $this->set_count_sql(
                 "SELECT COUNT(DISTINCT id) FROM {user} WHERE " . $tenantfield . " = :tenant",
-                ['tenant' => $tenant->get_identifier()]
+                ['tenant' => $tenant->get_sql_identifier()]
         );
 
         $this->set_sql($usertableextend->get_fields(), $usertableextend->get_from(),
diff --git a/classes/local/statistics_overview_table.php b/classes/local/statistics_overview_table.php
index ea888ca..5d4872e 100644
--- a/classes/local/statistics_overview_table.php
+++ b/classes/local/statistics_overview_table.php
@@ -61,10 +61,15 @@ public function __construct(
         $this->collapsible(false);
 
         $fields = 'model, modelinfo, COUNT(modelinfo) AS requestcount, SUM(value) AS userusage';
-        $from = '{local_ai_manager_request_log}';
-        $where = '1=1 GROUP BY modelinfo';
-        $this->set_sql($fields, $from, $where);
-        $this->set_count_sql('SELECT COUNT(DISTINCT modelinfo) FROM {local_ai_manager_request_log}');
+        $from = '{local_ai_manager_request_log} rl JOIN {user} u ON rl.userid = u.id';
+        $tenantfield = get_config('local_ai_manager', 'tenantcolumn');
+        $tenant = \core\di::get(tenant::class);
+        $where = 'u.' . $tenantfield . ' = :tenant GROUP BY modelinfo';
+        $params = ['tenant' => $tenant->get_sql_identifier()];
+        $this->set_sql($fields, $from, $where, $params);
+        $this->set_count_sql('SELECT COUNT(DISTINCT modelinfo) FROM {local_ai_manager_request_log} rl'
+                . ' JOIN {user} u ON rl.userid = u.id WHERE u.' . $tenantfield . ' = :tenant',
+                $params);
 
         parent::setup();
     }
diff --git a/classes/local/tenant.php b/classes/local/tenant.php
index a50ac96..6827d83 100644
--- a/classes/local/tenant.php
+++ b/classes/local/tenant.php
@@ -60,6 +60,15 @@ public function get_identifier(): string {
         return $this->identifier;
     }
 
+    /**
+     * Returns the identifier which needs to be used in SQL statements.
+     *
+     * @return string the tenant identifier for SQL statements
+     */
+    public function get_sql_identifier(): string {
+        return $this->is_default_tenant() ? '' : $this->identifier;
+    }
+
     /**
      * Returns if the current tenant of this object is the default tenant.
      *
diff --git a/classes/local/userinfo.php b/classes/local/userinfo.php
index 69ffadd..43c6988 100644
--- a/classes/local/userinfo.php
+++ b/classes/local/userinfo.php
@@ -17,7 +17,6 @@
 namespace local_ai_manager\local;
 
 use local_ai_manager\hook\userinfo_extend;
-use local_bycsauth\school;
 use stdClass;
 
 /**
diff --git a/classes/local/userstats_table.php b/classes/local/userstats_table.php
index 79c26de..33fa190 100644
--- a/classes/local/userstats_table.php
+++ b/classes/local/userstats_table.php
@@ -94,21 +94,24 @@ public function __construct(
             $from = '{local_ai_manager_request_log} rl LEFT JOIN {local_ai_manager_userinfo} ui ON rl.userid = ui.userid'
                     . ' JOIN {user} u ON u.id = rl.userid';
             $where = $tenantfield . ' = :tenant AND purpose = :purpose GROUP BY u.id';
-            $params = ['tenant' => $tenant->get_identifier(), 'purpose' => $purpose];
+            $params = [
+                    'tenant' => $tenant->get_sql_identifier(),
+                    'purpose' => $purpose,
+            ];
             $this->set_count_sql(
                     "SELECT COUNT(DISTINCT userid) FROM {local_ai_manager_request_log} rl JOIN {user} u ON rl.userid = u.id "
                     . "WHERE " . $tenantfield . " = :tenant AND purpose = :purpose",
-                    ['tenant' => $tenant->get_identifier(), 'purpose' => $purpose]
+                    $params
             );
         } else {
             $fields = 'u.id as id, lastname, firstname, COUNT(value) AS requestcount';
             $from =
-                    '{user} u LEFT JOIN {local_ai_manager_request_log} rl ON u.id = rl.userid';
-            $where = $tenantfield . ' = :tenant GROUP BY u.id';
-            $params = ['tenant' => $tenant->get_identifier()];
+                    '{local_ai_manager_request_log} rl LEFT JOIN {user} u ON rl.userid = u.id';
+            $where = 'u.' . $tenantfield . ' = :tenant GROUP BY u.id';
+            $params = ['tenant' => $tenant->get_sql_identifier()];
             $this->set_count_sql(
                     "SELECT COUNT(DISTINCT id) FROM {user} WHERE " . $tenantfield . " = :tenant",
-                    ['tenant' => $tenant->get_identifier()]
+                    $params
             );
         }
         $this->set_sql($fields, $from, $where, $params);
diff --git a/lang/de/local_ai_manager.php b/lang/de/local_ai_manager.php
index 9319204..21e5710 100644
--- a/lang/de/local_ai_manager.php
+++ b/lang/de/local_ai_manager.php
@@ -51,7 +51,7 @@
 $string['assignpurposes'] = 'Einsatzzwecke festlegen';
 $string['assignrole'] = 'Rolle zuweisen';
 $string['basicsettings'] = 'Grundeinstellungen';
-$string['basicsettingsdesc'] = 'Grundeinstellungn des AI-Managers konfigurieren';
+$string['basicsettingsdesc'] = 'Grundeinstellungen des AI-Managers konfigurieren';
 $string['configure_instance'] = 'KI-Tool-Instanzen konfigurieren';
 $string['configureaitool'] = 'KI-Tool konfigurieren';
 $string['configurepurposes'] = 'Einsatzzwecke konfigurieren';
diff --git a/purpose_statistics.php b/purpose_statistics.php
index 91365dd..a7d30fe 100644
--- a/purpose_statistics.php
+++ b/purpose_statistics.php
@@ -56,7 +56,7 @@
 $tenantfield = get_config('local_ai_manager', 'tenantcolumn');
 $recordscountsql = "SELECT COUNT(*) FROM {local_ai_manager_request_log} rl JOIN {user} u ON rl.userid = u.id"
         . " WHERE u." . $tenantfield . " = :tenant AND rl.purpose = :purpose";
-$recordscountparams = ['tenant' => $tenant->get_identifier(), 'purpose' => $purpose];
+$recordscountparams = ['tenant' => $tenant->get_sql_identifier(), 'purpose' => $purpose];
 $recordscount = $DB->count_records_sql($recordscountsql, $recordscountparams);
 
 if ($recordscount !== 0) {
diff --git a/rights_config.php b/rights_config.php
index 4041e10..ae38e68 100644
--- a/rights_config.php
+++ b/rights_config.php
@@ -25,7 +25,6 @@
 
 use local_ai_manager\local\userinfo;
 use local_ai_manager\output\tenantnavbar;
-use local_bycsauth\idmgroup;
 
 require_once(dirname(__FILE__) . '/../../config.php');
 require_login();
diff --git a/user_statistics.php b/user_statistics.php
index 6cf5ddb..ceff384 100644
--- a/user_statistics.php
+++ b/user_statistics.php
@@ -51,12 +51,12 @@
 $recordscount =
         $DB->count_records_sql("SELECT COUNT(*) FROM {local_ai_manager_request_log} rl JOIN {user} u ON rl.userid = u.id"
                 . " WHERE u." . $tenantfield . " = :tenant",
-                ['tenant' => $tenant->get_identifier()]);
+                ['tenant' => $tenant->get_sql_identifier()]);
 
 if ($recordscount !== 0) {
     $uniqid = 'statistics-table-users-all-purposes';
 
-    $baseurl = new moodle_url('/local/ai_manager/user_statistics.php', ['tenant' => $tenant->get_identifier()]);
+    $baseurl = new moodle_url('/local/ai_manager/user_statistics.php', ['tenant' => $tenant->get_sql_identifier()]);
     $table = new \local_ai_manager\local\userstats_table($uniqid, '', $tenant, $baseurl);
     $table->out(5, false);
 } else {