--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/plugins/calendar/drivers/database/SQL/mysql/2015022700.sql	Sat Jan 13 08:56:12 2018 -0500
@@ -0,0 +1,15 @@
+-- add identifier for recurring instances and exceptions
+
+ALTER TABLE `events` ADD `instance` varchar(16) NOT NULL DEFAULT '' AFTER `uid`;
+ALTER TABLE `events` ADD `isexception` tinyint(1) NOT NULL DEFAULT '0' AFTER `instance`;
+
+UPDATE `events` SET `instance` = DATE_FORMAT(`start`, '%Y%m%d')
+  WHERE `recurrence_id` != 0 AND `instance` = '' AND `all_day` = 1;
+
+UPDATE `events` SET `instance` = DATE_FORMAT(`start`, '%Y%m%dT%k%i%s')
+  WHERE `recurrence_id` != 0 AND `instance` = '' AND `all_day` = 0;
+
+-- extend alarms columns for multiple values
+
+ALTER TABLE `events` CHANGE `alarms` `alarms` TEXT NULL DEFAULT NULL;
+