diff --git a/src/Core/DB/DB.php b/src/Core/DB/DB.php
index 363dcc152d..4ed986e035 100644
--- a/src/Core/DB/DB.php
+++ b/src/Core/DB/DB.php
@@ -36,6 +36,7 @@ use App\Util\Exception\DuplicateFoundException;
 use App\Util\Exception\NotFoundException;
 use App\Util\Formatting;
 use Doctrine\Common\Collections\Criteria;
+use Doctrine\Common\Collections\Expr\Expression;
 use Doctrine\Common\Collections\ExpressionBuilder;
 use Doctrine\ORM\EntityManagerInterface;
 use Doctrine\ORM\Query;
@@ -109,7 +110,7 @@ abstract class DB
      *
      * @see self::findBy for the syntax
      */
-    private static function buildExpression(ExpressionBuilder $eb, array $criteria)
+    private static function buildExpression(ExpressionBuilder $eb, array $criteria): array
     {
         $expressions = [];
         foreach ($criteria as $op => $exp) {
@@ -117,16 +118,17 @@ abstract class DB
                 $method = "{$op}X";
                 $expr   = self::buildExpression($eb, $exp);
                 if (is_array($expr)) {
-                    return $eb->{$method}(...$expr);
+                    $expressions[] = $eb->{$method}(...$expr);
                 } else {
-                    return $eb->{$method}($expr);
+                    $expressions[] = $eb->{$method}($expr);
                 }
             } elseif ($op == 'is_null') {
                 $expressions[] = $eb->isNull($exp);
             } else {
                 if (in_array($op, self::$find_by_ops)) {
-                    $method        = Formatting::snakeCaseToCamelCase($op);
-                    $expressions[] = $eb->{$method}(...$exp);
+                    foreach ($exp as $field => $value) {
+                        $expressions[] = $eb->{$op}($field, $value);
+                    }
                 } else {
                     $expressions[] = $eb->eq($op, $exp);
                 }
@@ -151,7 +153,8 @@ abstract class DB
         if (empty($ops)) {
             return $repo->findBy($criteria, $orderBy, $limit, $offset);
         } else {
-            $criteria = new Criteria(self::buildExpression(Criteria::expr(), $criteria), $orderBy, $offset, $limit);
+            $eb       = Criteria::expr();
+            $criteria = new Criteria($eb->andX(...self::buildExpression($eb, $criteria)), $orderBy, $offset, $limit);
             return $repo->matching($criteria)->toArray(); // Always work with array or it becomes really complicated
         }
     }
@@ -161,7 +164,7 @@ abstract class DB
      */
     public static function findOneBy(string $table, array $criteria, ?array $orderBy = null, ?int $offset = null)
     {
-        $res = self::findBy($table, $criteria, $orderBy, 1, $offset);
+        $res = self::findBy($table, $criteria, $orderBy, 2, $offset);
         if (count($res) == 1) {
             return $res[0];
         } else {
@@ -176,7 +179,7 @@ abstract class DB
     public static function count(string $table, array $criteria)
     {
         $repo = self::getRepository($table);
-        return $repo->count($table, $criteria);
+        return $repo->count($criteria);
     }
 
     /**
diff --git a/tests/Core/DB/DBTest.php b/tests/Core/DB/DBTest.php
new file mode 100644
index 0000000000..53efdcd2c1
--- /dev/null
+++ b/tests/Core/DB/DBTest.php
@@ -0,0 +1,88 @@
+<?php
+
+// {{{ License
+// This file is part of GNU social - https://www.gnu.org/software/social
+//
+// GNU social is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// GNU social is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with GNU social.  If not, see <http://www.gnu.org/licenses/>.
+// }}}
+
+namespace App\Tests\Core\DB;
+
+use App\Core\DB\DB;
+use App\Entity\GSActor;
+use App\Entity\LocalUser;
+use App\Util\Exception\DuplicateFoundException;
+use App\Util\Exception\NotFoundException;
+use App\Util\GNUsocialTestCase;
+use Jchook\AssertThrows\AssertThrows;
+
+class DBTest extends GNUsocialTestCase
+{
+    use AssertThrows;
+
+    public function testDql()
+    {
+        static::bootKernel();
+        $actor = DB::dql('select a from gsactor a where a.nickname = :nickname', ['nickname' => 'taken_user']);
+        static::assertTrue(is_array($actor));
+        static::assertTrue($actor[0] instanceof GSActor);
+    }
+
+    public function testSql()
+    {
+        static::bootKernel();
+        $actor = DB::sql('select {select} from gsactor a where a.nickname = :nickname', ['a' => 'App\Entity\GSActor'], ['nickname' => 'taken_user']);
+        static::assertTrue(is_array($actor));
+        static::assertTrue($actor[0] instanceof GSActor);
+    }
+
+    public function testFindBy()
+    {
+        static::bootKernel();
+        $actor = DB::findBy('gsactor', ['nickname' => 'taken_user']);
+        static::assertTrue(is_array($actor));
+        static::assertTrue($actor[0] instanceof GSActor);
+
+        $actor = DB::findBy('gsactor', ['and' => ['nickname' => 'taken_user', 'is_null' => 'bio', 'gte' => ['id' => 0], 'or' => ['normalized_nickname' => 'takenuser']]]);
+        static::assertTrue(is_array($actor));
+        static::assertTrue($actor[0] instanceof GSActor);
+    }
+
+    public function testFindOneBy()
+    {
+        static::bootKernel();
+        $actor = DB::findOneBy('gsactor', ['nickname' => 'taken_user']);
+        static::assertTrue($actor instanceof GSActor);
+
+        static::assertThrows(DuplicateFoundException::class, fn () => DB::findOneBy('gsactor', ['is_null' => 'bio']));
+        static::assertThrows(NotFoundException::class, fn () => DB::findOneBy('gsactor', ['nickname' => 'nickname_not_in_use']));
+    }
+
+    public function testCount()
+    {
+        static::bootKernel();
+        static::assertTrue(DB::count('gsactor', ['nickname' => 'taken_user']) == 1);
+        static::assertTrue(DB::count('gsactor', []) != 1);
+    }
+
+    public function testPersistWithSameId()
+    {
+        $actor = GSActor::create(['nickname' => 'test', 'normalized_nickname' => 'test']);
+        $user  = LocalUser::create(['nickname' => 'test']);
+        $id    = DB::persistWithSameId($actor, $user, fn ($id) => $id);
+        static::assertTrue($id != 0);
+        static::assertTrue($actor->getId() == $id);
+        static::assertTrue($user->getId() == $id);
+    }
+}