diff --git a/Classes/Domain/Repository/LogRepository.php b/Classes/Domain/Repository/LogRepository.php
index 0995744..7911712 100644
--- a/Classes/Domain/Repository/LogRepository.php
+++ b/Classes/Domain/Repository/LogRepository.php
@@ -30,7 +30,7 @@ public function getNumberOfReceivers(Filter $filter): int
             . ' left join ' . Newsletter::TABLE_NAME . ' nl on nl.uid=l.newsletter'
             . ' left join ' . Configuration::TABLE_NAME . ' c on nl.configuration=c.uid'
             . ' where l.deleted=0 and l.status=' . Log::STATUS_DISPATCH
-            . ' and c.site in ("' . implode('","', $filter->getSitesForFilter()) . '")'
+            . ' and c.site in (\'' . implode('\',\'', $filter->getSitesForFilter()) . '\')'
             . ' and nl.crdate>' . $filter->getTimeDateStart()->getTimestamp()
             . ' limit 1';
         return (int)$connection->executeQuery($sql)->fetchOne();
@@ -57,7 +57,7 @@ public function getGroupedLinksByHref(Filter $filter): array
             . ' left join ' . Newsletter::TABLE_NAME . ' nl on nl.uid=l.newsletter'
             . ' left join ' . Configuration::TABLE_NAME . ' c on nl.configuration=c.uid'
             . ' where l.deleted=0 and l.status=' . Log::STATUS_LINKOPENING
-            . ' and c.site in ("' . implode('","', $filter->getSitesForFilter()) . '")'
+            . ' and c.site in (\'' . implode('\',\'', $filter->getSitesForFilter()) . '\')'
             . ' and nl.crdate>' . $filter->getTimeDateStart()->getTimestamp()
             . ' group by l.properties, l.newsletter'
             . ' order by count desc'
@@ -79,13 +79,13 @@ public function getGroupedLinksByHref(Filter $filter): array
     public function getOverallOpenings(Filter $filter): int
     {
         $connection = DatabaseUtility::getConnectionForTable(Log::TABLE_NAME);
-        $sql = 'select count(distinct newsletter, user)'
+        $sql = 'select count(distinct (newsletter, user))'
             . ' from ' . Log::TABLE_NAME . ' l'
             . ' left join ' . Newsletter::TABLE_NAME . ' nl on nl.uid=l.newsletter'
             . ' left join ' . Configuration::TABLE_NAME . ' c on nl.configuration=c.uid'
             . ' where l.deleted = 0'
             . ' and l.status IN (' . Log::STATUS_NEWSLETTEROPENING . ',' . Log::STATUS_LINKOPENING . ')'
-            . ' and c.site in ("' . implode('","', $filter->getSitesForFilter()) . '")'
+            . ' and c.site in (\'' . implode('\',\'', $filter->getSitesForFilter()) . '\')'
             . ' and nl.crdate>' . $filter->getTimeDateStart()->getTimestamp();
         return (int)$connection->executeQuery($sql)->fetchOne();
     }
@@ -98,12 +98,12 @@ public function getOverallOpenings(Filter $filter): int
     public function getOpeningsByClickers(Filter $filter): int
     {
         $connection = DatabaseUtility::getConnectionForTable(Log::TABLE_NAME);
-        $sql = 'select count(distinct newsletter, user)'
+        $sql = 'select count(distinct (newsletter, user))'
             . ' from ' . Log::TABLE_NAME . ' l'
             . ' left join ' . Newsletter::TABLE_NAME . ' nl on nl.uid=l.newsletter'
             . ' left join ' . Configuration::TABLE_NAME . ' c on nl.configuration=c.uid'
             . ' where l.deleted = 0 and l.status=' . Log::STATUS_LINKOPENING
-            . ' and c.site in ("' . implode('","', $filter->getSitesForFilter()) . '")'
+            . ' and c.site in (\'' . implode('\',\'', $filter->getSitesForFilter()) . '\')'
             . ' and nl.crdate>' . $filter->getTimeDateStart()->getTimestamp();
         return (int)$connection->executeQuery($sql)->fetchOne();
     }
@@ -152,7 +152,7 @@ protected function getOverallAmountByLogStatus(array $status, Filter $filter): i
             . ' left join ' . Newsletter::TABLE_NAME . ' nl on nl.uid=l.newsletter'
             . ' left join ' . Configuration::TABLE_NAME . ' c on nl.configuration=c.uid'
             . ' where l.deleted = 0 and l.status in (' . ArrayUtility::convertArrayToIntegerList($status) . ')'
-            . ' and c.site in ("' . implode('","', $filter->getSitesForFilter()) . '")'
+            . ' and c.site in (\'' . implode('\',\'', $filter->getSitesForFilter()) . '\')'
             . ' and nl.crdate>' . $filter->getTimeDateStart()->getTimestamp();
         return (int)$connection->executeQuery($sql)->fetchOne();
     }
@@ -275,7 +275,7 @@ public function isLogRecordExisting(int $newsletterIdentifier, int $userIdentifi
         $uid = (int)$queryBuilder
             ->select('uid')
             ->from(Log::TABLE_NAME)
-            ->where('newsletter=' . $newsletterIdentifier . ' and user=' . $userIdentifier . ' and status=' . $status)
+            ->where('newsletter=' . $newsletterIdentifier . ' and user=\'' . $userIdentifier . '\' and status=\'' . $status . '\'')
             ->setMaxResults(1)
             ->executeQuery()
             ->fetchOne();
@@ -312,7 +312,7 @@ public function findByNewsletterAndStatus(Newsletter $newsletter, array $status,
     public function findRawByUser(User $user, array $statusWhitelist = [], array $statusBlacklist = []): array
     {
         $connection = DatabaseUtility::getConnectionForTable(Log::TABLE_NAME);
-        $sql = 'select * from ' . Log::TABLE_NAME . ' where deleted=0 and user=' . $user->getUid();
+        $sql = 'select * from ' . Log::TABLE_NAME . ' where deleted=0 and user=\'' . $user->getUid() . '\'';
         if ($statusWhitelist !== []) {
             $sql .= ' and status in (' . implode(',', $statusWhitelist) . ')';
         } elseif ($statusBlacklist !== []) {
diff --git a/Classes/Domain/Repository/QueueRepository.php b/Classes/Domain/Repository/QueueRepository.php
index 2d4e2db..30c51b2 100644
--- a/Classes/Domain/Repository/QueueRepository.php
+++ b/Classes/Domain/Repository/QueueRepository.php
@@ -94,7 +94,7 @@ public function isUserAndNewsletterAlreadyAddedToQueue(User $user, Newsletter $n
         return (int)$queryBuilder
             ->select('uid')
             ->from(Queue::TABLE_NAME)
-            ->where('newsletter=' . $newsletter->getUid() . ' and user=' . $user->getUid())
+            ->where('newsletter=' . $newsletter->getUid() . ' and user=\'' . $user->getUid() . '\'')
             ->setMaxResults(1)
             ->executeQuery()
             ->fetchOne() > 0;
diff --git a/Classes/Domain/Repository/UserRepository.php b/Classes/Domain/Repository/UserRepository.php
index 176ecdf..160e867 100644
--- a/Classes/Domain/Repository/UserRepository.php
+++ b/Classes/Domain/Repository/UserRepository.php
@@ -96,7 +96,7 @@ public function getUserAmountFromGroups(array $groupIdentifiers): int
                 }
                 $sub .= 'find_in_set(' . (int)$identifier . ',usergroup)';
             }
-            $sql .= ' where deleted=0 and disable=0 and email like "%@%" and (' . $sub . ')';
+            $sql .= ' where deleted=0 and disable=0 and email like \'%@%\' and (' . $sub . ')';
             return (int)$connection->executeQuery($sql)->fetchOne();
         }
         return 0;