diff --git a/php/database/photos_table.sql b/php/database/photos_table.sql
index 7e4f0fb..b87f0b9 100644
--- a/php/database/photos_table.sql
+++ b/php/database/photos_table.sql
@@ -22,9 +22,9 @@ CREATE TABLE IF NOT EXISTS `?` (
   `star` tinyint(1) NOT NULL,
   `thumbUrl` char(37) NOT NULL,
   `album` bigint(20) unsigned NOT NULL,
-  `checksum` char(40) DEFAULT NULL,
+  `checksum` char(40) NOT NULL UNIQUE,
   `medium` tinyint(1) NOT NULL DEFAULT '0',
   PRIMARY KEY (`id`),
   KEY `Index_album` (`album`),
   KEY `Index_star` (`star`)
-) ENGINE=MyISAM DEFAULT CHARSET=utf8;
\ No newline at end of file
+) ENGINE=MyISAM DEFAULT CHARSET=utf8;