diff --git a/tools/resources/database/structure.sql b/tools/resources/database/structure.sql
index b0b723e..1e1da9b 100644
--- a/tools/resources/database/structure.sql
+++ b/tools/resources/database/structure.sql
@@ -29,10 +29,10 @@ CREATE TABLE `tbl_cron` (
   `id` int(8) unsigned NOT NULL AUTO_INCREMENT,
   `title` varchar(200) NOT NULL DEFAULT '',
   `slug` varchar(200) NOT NULL DEFAULT '',
-  `description` varchar(200) DEFAULT NULL,
+  `description` varchar(200) NOT NULL DEFAULT '',
   `run_every` int(8) unsigned NOT NULL DEFAULT 60 COMMENT 'in seconds',
-  `last_run` bigint(20) unsigned DEFAULT NULL,
-  `next_run` bigint(20) unsigned DEFAULT NULL,
+  `last_run` int(11) unsigned NOT NULL DEFAULT 0,
+  `next_run` int(11) unsigned NOT NULL DEFAULT 0,
   `run_time` float(7,3) unsigned NOT NULL DEFAULT 0.000,
   `cron_state` tinyint(1) unsigned NOT NULL DEFAULT 0,
   `is_enabled` int(1) unsigned NOT NULL DEFAULT 1,