diff --git a/framework/yii/db/ActiveRecord.php b/framework/yii/db/ActiveRecord.php
index 9edc824..e13bf90 100644
--- a/framework/yii/db/ActiveRecord.php
+++ b/framework/yii/db/ActiveRecord.php
@@ -1485,18 +1485,19 @@ class ActiveRecord extends Model
 	}
 
 	/**
-	 * @param array $keys
-	 * @return boolean
+	 * Returns a value indicating whether the given set of attributes represents the primary key for this model
+	 * @param array $keys the set of attributes to check
+	 * @return boolean whether the given set of attributes represents the primary key for this model
 	 */
-	private function isPrimaryKey($keys)
+	public static function isPrimaryKey($keys)
 	{
-		$pks = $this->primaryKey();
+		$pks = static::primaryKey();
 		foreach ($keys as $key) {
 			if (!in_array($key, $pks, true)) {
 				return false;
 			}
 		}
-		return true;
+		return count($keys) === count($pks);
 	}
 
 	/**
diff --git a/tests/unit/framework/db/ActiveRecordTest.php b/tests/unit/framework/db/ActiveRecordTest.php
index f96f2d3..b2981f2 100644
--- a/tests/unit/framework/db/ActiveRecordTest.php
+++ b/tests/unit/framework/db/ActiveRecordTest.php
@@ -489,4 +489,21 @@ class ActiveRecordTest extends DatabaseTestCase
 		$customers = Customer::find()->where(['status' => false])->all();
 		$this->assertEquals(1, count($customers));
 	}
+
+	public function testIsPrimaryKey()
+	{
+		$this->assertFalse(Customer::isPrimaryKey([]));
+		$this->assertTrue(Customer::isPrimaryKey(['id']));
+		$this->assertFalse(Customer::isPrimaryKey(['id', 'name']));
+		$this->assertFalse(Customer::isPrimaryKey(['name']));
+		$this->assertFalse(Customer::isPrimaryKey(['name', 'email']));
+
+		$this->assertFalse(OrderItem::isPrimaryKey([]));
+		$this->assertFalse(OrderItem::isPrimaryKey(['order_id']));
+		$this->assertFalse(OrderItem::isPrimaryKey(['item_id']));
+		$this->assertFalse(OrderItem::isPrimaryKey(['quantity']));
+		$this->assertFalse(OrderItem::isPrimaryKey(['quantity', 'subtotal']));
+		$this->assertTrue(OrderItem::isPrimaryKey(['order_id', 'item_id']));
+		$this->assertFalse(OrderItem::isPrimaryKey(['order_id', 'item_id', 'quantity']));
+	}
 }