diff --git a/system/Validation/Rules.php b/system/Validation/Rules.php
index 40a5955b157d..93b86ea6b1dd 100644
--- a/system/Validation/Rules.php
+++ b/system/Validation/Rules.php
@@ -86,7 +86,11 @@ public function greater_than_equal_to(?string $str, string $min): bool
     public function is_not_unique(?string $str, string $field, array $data): bool
     {
         // Grab any data for exclusion of a single row.
-        [$field, $whereField, $whereValue] = array_pad(explode(',', $field), 3, null);
+        [$field, $whereField, $whereValue] = array_pad(
+            explode(',', $field),
+            3,
+            null
+        );
 
         // Break the table and field apart
         sscanf($field, '%[^.].%[^.]', $table, $field);
@@ -97,7 +101,10 @@ public function is_not_unique(?string $str, string $field, array $data): bool
             ->where($field, $str)
             ->limit(1);
 
-        if (! empty($whereField) && ! empty($whereValue) && ! preg_match('/^\{(\w+)\}$/', $whereValue)) {
+        if (
+            ! empty($whereField) && ! empty($whereValue)
+            && ! preg_match('/^\{(\w+)\}$/', $whereValue)
+        ) {
             $row = $row->where($whereField, $whereValue);
         }
 
@@ -125,7 +132,11 @@ public function in_list(?string $value, string $list): bool
      */
     public function is_unique(?string $str, string $field, array $data): bool
     {
-        [$field, $ignoreField, $ignoreValue] = array_pad(explode(',', $field), 3, null);
+        [$field, $ignoreField, $ignoreValue] = array_pad(
+            explode(',', $field),
+            3,
+            null
+        );
 
         sscanf($field, '%[^.].%[^.]', $table, $field);
 
@@ -135,7 +146,10 @@ public function is_unique(?string $str, string $field, array $data): bool
             ->where($field, $str)
             ->limit(1);
 
-        if (! empty($ignoreField) && ! empty($ignoreValue) && ! preg_match('/^\{(\w+)\}$/', $ignoreValue)) {
+        if (
+            ! empty($ignoreField) && ! empty($ignoreValue)
+            && ! preg_match('/^\{(\w+)\}$/', $ignoreValue)
+        ) {
             $row = $row->where("{$ignoreField} !=", $ignoreValue);
         }
 
diff --git a/system/Validation/StrictRules/Rules.php b/system/Validation/StrictRules/Rules.php
index 47dbee9b5ae7..05d9e96a305b 100644
--- a/system/Validation/StrictRules/Rules.php
+++ b/system/Validation/StrictRules/Rules.php
@@ -117,7 +117,34 @@ public function greater_than_equal_to($str, string $min): bool
      */
     public function is_not_unique($str, string $field, array $data): bool
     {
-        return $this->nonStrictRules->is_not_unique($str, $field, $data);
+        if (is_object($str) || is_array($str)) {
+            return false;
+        }
+
+        // Grab any data for exclusion of a single row.
+        [$field, $whereField, $whereValue] = array_pad(
+            explode(',', $field),
+            3,
+            null
+        );
+
+        // Break the table and field apart
+        sscanf($field, '%[^.].%[^.]', $table, $field);
+
+        $row = Database::connect($data['DBGroup'] ?? null)
+            ->table($table)
+            ->select('1')
+            ->where($field, $str)
+            ->limit(1);
+
+        if (
+            ! empty($whereField) && ! empty($whereValue)
+            && ! preg_match('/^\{(\w+)\}$/', $whereValue)
+        ) {
+            $row = $row->where($whereField, $whereValue);
+        }
+
+        return $row->get()->getRow() !== null;
     }
 
     /**
@@ -151,7 +178,32 @@ public function in_list($value, string $list): bool
      */
     public function is_unique($str, string $field, array $data): bool
     {
-        return $this->nonStrictRules->is_unique($str, $field, $data);
+        if (is_object($str) || is_array($str)) {
+            return false;
+        }
+
+        [$field, $ignoreField, $ignoreValue] = array_pad(
+            explode(',', $field),
+            3,
+            null
+        );
+
+        sscanf($field, '%[^.].%[^.]', $table, $field);
+
+        $row = Database::connect($data['DBGroup'] ?? null)
+            ->table($table)
+            ->select('1')
+            ->where($field, $str)
+            ->limit(1);
+
+        if (
+            ! empty($ignoreField) && ! empty($ignoreValue)
+            && ! preg_match('/^\{(\w+)\}$/', $ignoreValue)
+        ) {
+            $row = $row->where("{$ignoreField} !=", $ignoreValue);
+        }
+
+        return $row->get()->getRow() === null;
     }
 
     /**
diff --git a/tests/system/Validation/DatabaseRelatedRulesTest.php b/tests/system/Validation/DatabaseRelatedRulesTest.php
index 42881bab444e..e9abd11f83aa 100644
--- a/tests/system/Validation/DatabaseRelatedRulesTest.php
+++ b/tests/system/Validation/DatabaseRelatedRulesTest.php
@@ -11,10 +11,7 @@
 
 namespace CodeIgniter\Validation;
 
-use CodeIgniter\Test\CIUnitTestCase;
-use CodeIgniter\Test\DatabaseTestTrait;
-use Config\Database;
-use Config\Services;
+use CodeIgniter\Validation\StrictRules\DatabaseRelatedRulesTest as StrictDatabaseRelatedRulesTest;
 use Tests\Support\Validation\TestRules;
 
 /**
@@ -22,12 +19,9 @@
  *
  * @group DatabaseLive
  */
-final class DatabaseRelatedRulesTest extends CIUnitTestCase
+final class DatabaseRelatedRulesTest extends StrictDatabaseRelatedRulesTest
 {
-    use DatabaseTestTrait;
-
-    private Validation $validation;
-    private array $config = [
+    protected array $config = [
         'ruleSets' => [
             Rules::class,
             FormatRules::class,
@@ -45,173 +39,8 @@ final class DatabaseRelatedRulesTest extends CIUnitTestCase
         ],
     ];
 
-    protected function setUp(): void
-    {
-        parent::setUp();
-        $this->validation = new Validation((object) $this->config, Services::renderer());
-        $this->validation->reset();
-    }
-
-    public function testIsUniqueFalse(): void
-    {
-        Database::connect()
-            ->table('user')
-            ->insert([
-                'name'    => 'Derek Travis',
-                'email'   => 'derek@world.com',
-                'country' => 'Elbonia',
-            ]);
-
-        $data = ['email' => 'derek@world.com'];
-        $this->validation->setRules(['email' => 'is_unique[user.email]']);
-        $this->assertFalse($this->validation->run($data));
-    }
-
-    public function testIsUniqueTrue(): void
-    {
-        $data = ['email' => 'derek@world.co.uk'];
-        $this->validation->setRules(['email' => 'is_unique[user.email]']);
-        $this->assertTrue($this->validation->run($data));
-    }
-
-    public function testIsUniqueIgnoresParams(): void
-    {
-        $db = Database::connect();
-        $db
-            ->table('user')
-            ->insert([
-                'name'    => 'Developer A',
-                'email'   => 'deva@example.com',
-                'country' => 'Elbonia',
-            ]);
-        $row = $db->table('user')
-            ->limit(1)
-            ->get()
-            ->getRow();
-
-        $data = ['email' => 'derek@world.co.uk'];
-        $this->validation->setRules(['email' => "is_unique[user.email,id,{$row->id}]"]);
-        $this->assertTrue($this->validation->run($data));
-    }
-
-    public function testIsUniqueIgnoresParamsPlaceholders(): void
-    {
-        $this->hasInDatabase('user', [
-            'name'    => 'Derek',
-            'email'   => 'derek@world.co.uk',
-            'country' => 'GB',
-        ]);
-
-        $row = Database::connect()
-            ->table('user')
-            ->limit(1)
-            ->get()
-            ->getRow();
-
-        $data = [
-            'id'    => $row->id,
-            'email' => 'derek@world.co.uk',
-        ];
-
-        $this->validation->setRules(['email' => 'is_unique[user.email,id,{id}]']);
-        $this->assertTrue($this->validation->run($data));
-    }
-
-    public function testIsUniqueByManualRun(): void
-    {
-        Database::connect()
-            ->table('user')
-            ->insert([
-                'name'    => 'Developer A',
-                'email'   => 'deva@example.com',
-                'country' => 'Elbonia',
-            ]);
-
-        $this->assertFalse((new Rules())->is_unique('deva@example.com', 'user.email,id,{id}', []));
-    }
-
-    public function testIsNotUniqueFalse(): void
-    {
-        Database::connect()
-            ->table('user')
-            ->insert([
-                'name'    => 'Derek Travis',
-                'email'   => 'derek@world.com',
-                'country' => 'Elbonia',
-            ]);
-
-        $data = ['email' => 'derek1@world.com'];
-        $this->validation->setRules(['email' => 'is_not_unique[user.email]']);
-        $this->assertFalse($this->validation->run($data));
-    }
-
-    public function testIsNotUniqueTrue(): void
-    {
-        Database::connect()
-            ->table('user')
-            ->insert([
-                'name'    => 'Derek Travis',
-                'email'   => 'derek@world.com',
-                'country' => 'Elbonia',
-            ]);
-
-        $data = ['email' => 'derek@world.com'];
-        $this->validation->setRules(['email' => 'is_not_unique[user.email]']);
-        $this->assertTrue($this->validation->run($data));
-    }
-
-    public function testIsNotUniqueIgnoresParams(): void
+    protected function createRules()
     {
-        $db = Database::connect();
-        $db->table('user')
-            ->insert([
-                'name'    => 'Developer A',
-                'email'   => 'deva@example.com',
-                'country' => 'Elbonia',
-            ]);
-
-        $row = $db->table('user')
-            ->limit(1)
-            ->get()
-            ->getRow();
-
-        $data = ['email' => 'derek@world.co.uk'];
-        $this->validation->setRules(['email' => "is_not_unique[user.email,id,{$row->id}]"]);
-        $this->assertFalse($this->validation->run($data));
-    }
-
-    public function testIsNotUniqueIgnoresParamsPlaceholders(): void
-    {
-        $this->hasInDatabase('user', [
-            'name'    => 'Derek',
-            'email'   => 'derek@world.co.uk',
-            'country' => 'GB',
-        ]);
-
-        $row = Database::connect()
-            ->table('user')
-            ->limit(1)
-            ->get()
-            ->getRow();
-
-        $data = [
-            'id'    => $row->id,
-            'email' => 'derek@world.co.uk',
-        ];
-        $this->validation->setRules(['email' => 'is_not_unique[user.email,id,{id}]']);
-        $this->assertTrue($this->validation->run($data));
-    }
-
-    public function testIsNotUniqueByManualRun(): void
-    {
-        Database::connect()
-            ->table('user')
-            ->insert([
-                'name'    => 'Developer A',
-                'email'   => 'deva@example.com',
-                'country' => 'Elbonia',
-            ]);
-
-        $this->assertTrue((new Rules())->is_not_unique('deva@example.com', 'user.email,id,{id}', []));
+        return new Rules();
     }
 }
diff --git a/tests/system/Validation/StrictRules/DatabaseRelatedRulesTest.php b/tests/system/Validation/StrictRules/DatabaseRelatedRulesTest.php
index 79c9c7d39e9f..9b56dc3e3205 100644
--- a/tests/system/Validation/StrictRules/DatabaseRelatedRulesTest.php
+++ b/tests/system/Validation/StrictRules/DatabaseRelatedRulesTest.php
@@ -21,14 +21,16 @@
 /**
  * @internal
  *
+ * @no-final
+ *
  * @group DatabaseLive
  */
-final class DatabaseRelatedRulesTest extends CIUnitTestCase
+class DatabaseRelatedRulesTest extends CIUnitTestCase
 {
     use DatabaseTestTrait;
 
-    private Validation $validation;
-    private array $config = [
+    protected Validation $validation;
+    protected array $config = [
         'ruleSets' => [
             Rules::class,
             FormatRules::class,
@@ -53,6 +55,11 @@ protected function setUp(): void
         $this->validation->reset();
     }
 
+    protected function createRules()
+    {
+        return new Rules();
+    }
+
     public function testIsUniqueFalse(): void
     {
         Database::connect()
@@ -128,7 +135,22 @@ public function testIsUniqueByManualRun(): void
                 'country' => 'Elbonia',
             ]);
 
-        $this->assertFalse((new Rules())->is_unique('deva@example.com', 'user.email,id,{id}', []));
+        $this->assertFalse($this->createRules()->is_unique('deva@example.com', 'user.email,id,{id}', []));
+    }
+
+    public function testIsUniqueIntValueByManualRun(): void
+    {
+        Database::connect()
+            ->table('user')
+            ->insert([
+                'name'    => 'Developer A',
+                'email'   => 'deva@example.com',
+                'country' => 'Elbonia',
+            ]);
+
+        $result = $this->createRules()->is_unique(1, 'user.id', []);
+
+        $this->assertFalse($result);
     }
 
     public function testIsNotUniqueFalse(): void
@@ -213,6 +235,6 @@ public function testIsNotUniqueByManualRun(): void
                 'country' => 'Elbonia',
             ]);
 
-        $this->assertTrue((new Rules())->is_not_unique('deva@example.com', 'user.email,id,{id}', []));
+        $this->assertTrue($this->createRules()->is_not_unique('deva@example.com', 'user.email,id,{id}', []));
     }
 }