修复oracle数据库ping语句 (#721)

* 修复oracle数据库ping语句

* fix coding standard

Author: imzhi

src/Db/Drivers/TPdoDriver.php

@@ -82,7 +82,9 @@ public function ping(): bool
         }
         try
         {
-            if ($instance->query('select 1'))
+            $driverName = $this->instance->getAttribute(\PDO::ATTR_DRIVER_NAME);
+            $is_oci = 'oci' === $driverName;
+            if ($instance->query($is_oci ? 'select 1 from dual' : 'select 1'))
             {
                 return true;
             }