diff --git a/plugins/calendar/drivers/caldav/SQL/mysql.initial.sql b/plugins/calendar/drivers/caldav/SQL/mysql.initial.sql
new file mode 100644
index 0000000..569c5e6
--- /dev/null
+++ b/plugins/calendar/drivers/caldav/SQL/mysql.initial.sql
@@ -0,0 +1,28 @@
+DROP TABLE `kolab_alarms` IF EXISTS;
+
+CREATE TABLE IF NOT EXISTS `kolab_alarms` (
+  `alarm_id` VARCHAR(255) NOT NULL,
+  `user_id` int(10) UNSIGNED NOT NULL,
+  `notifyat` DATETIME DEFAULT NULL,
+  `dismissed` TINYINT(3) UNSIGNED NOT NULL DEFAULT '0',
+  PRIMARY KEY(`alarm_id`,`user_id`),
+  CONSTRAINT `fk_kolab_alarms_user_id` FOREIGN KEY (`user_id`)
+    REFERENCES `users`(`user_id`) ON DELETE CASCADE ON UPDATE CASCADE
+) ROW_FORMAT=DYNAMIC ENGINE=INNODB CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
+
+DROP TABLE `itipinvitations` IF EXISTS;
+
+CREATE TABLE IF NOT EXISTS `itipinvitations` (
+  `token` VARCHAR(64) NOT NULL,
+  `event_uid` VARCHAR(255) NOT NULL,
+  `user_id` int(10) UNSIGNED NOT NULL DEFAULT '0',
+  `event` TEXT NOT NULL,
+  `expires` DATETIME DEFAULT NULL,
+  `cancelled` TINYINT(3) UNSIGNED NOT NULL DEFAULT '0',
+  PRIMARY KEY(`token`),
+  INDEX `uid_idx` (`event_uid`,`user_id`),
+  CONSTRAINT `fk_itipinvitations_user_id` FOREIGN KEY (`user_id`)
+    REFERENCES `users`(`user_id`) ON DELETE CASCADE ON UPDATE CASCADE
+) ROW_FORMAT=DYNAMIC ENGINE=INNODB CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
+
+REPLACE INTO `system` (`name`, `value`) VALUES ('calendar-caldav-version', '2021102600');
diff --git a/plugins/calendar/drivers/caldav/SQL/oracle.initial.sql b/plugins/calendar/drivers/caldav/SQL/oracle.initial.sql
new file mode 100644
index 0000000..5c475a6
--- /dev/null
+++ b/plugins/calendar/drivers/caldav/SQL/oracle.initial.sql
@@ -0,0 +1,24 @@
+CREATE TABLE "kolab_alarms" (
+    "alarm_id" varchar(255) NOT NULL PRIMARY KEY,
+    "user_id" integer NOT NULL
+        REFERENCES "users" ("user_id") ON DELETE CASCADE,
+    "notifyat" timestamp DEFAULT NULL,
+    "dismissed" smallint DEFAULT 0 NOT NULL
+);
+
+CREATE INDEX "kolab_alarms_user_id_idx" ON "kolab_alarms" ("user_id");
+
+
+CREATE TABLE "itipinvitations" (
+    "token" varchar(64) NOT NULL PRIMARY KEY,
+    "event_uid" varchar(255) NOT NULL,
+    "user_id" integer NOT NULL
+        REFERENCES "users" ("user_id") ON DELETE CASCADE,
+    "event" long NOT NULL,
+    "expires" timestamp DEFAULT NULL,
+    "cancelled" smallint DEFAULT 0 NOT NULL
+);
+
+CREATE INDEX "itipinvitations_user_id_idx" ON "itipinvitations" ("user_id", "event_uid");
+
+INSERT INTO "system" ("name", "value") VALUES ('calendar-caldav-version', '2014041700');
diff --git a/plugins/calendar/drivers/caldav/SQL/postgres.initial.sql b/plugins/calendar/drivers/caldav/SQL/postgres.initial.sql
new file mode 100644
index 0000000..1532b5a
--- /dev/null
+++ b/plugins/calendar/drivers/caldav/SQL/postgres.initial.sql
@@ -0,0 +1,25 @@
+CREATE TABLE IF NOT EXISTS kolab_alarms (
+  alarm_id character varying(255) NOT NULL,
+  user_id integer NOT NULL
+        REFERENCES users (user_id) ON DELETE CASCADE ON UPDATE CASCADE,
+  notifyat timestamp without time zone DEFAULT NULL,
+  dismissed smallint NOT NULL DEFAULT 0,
+  PRIMARY KEY(alarm_id)
+);
+
+CREATE INDEX kolab_alarms_user_id_idx ON kolab_alarms (user_id);
+
+CREATE TABLE IF NOT EXISTS itipinvitations (
+  token character varying(64) NOT NULL,
+  event_uid character varying(255) NOT NULL,
+  user_id integer NOT NULL
+        REFERENCES users (user_id) ON DELETE CASCADE ON UPDATE CASCADE,
+  event text NOT NULL,
+  expires timestamp without time zone DEFAULT NULL,
+  cancelled smallint NOT NULL DEFAULT 0,
+  PRIMARY KEY(token)
+);
+
+CREATE INDEX itipinvitations_user_id_event_uid_idx ON itipinvitations (user_id, event_uid);
+
+INSERT INTO system (name, value) VALUES ('calendar-caldav-version', '2014041700');
diff --git a/plugins/calendar/drivers/caldav/SQL/sqlite.initial.sql b/plugins/calendar/drivers/caldav/SQL/sqlite.initial.sql
new file mode 100644
index 0000000..6730e87
--- /dev/null
+++ b/plugins/calendar/drivers/caldav/SQL/sqlite.initial.sql
@@ -0,0 +1,22 @@
+CREATE TABLE kolab_alarms (
+  alarm_id VARCHAR(255) NOT NULL,
+  user_id INTEGER NOT NULL,
+  notifyat DATETIME DEFAULT NULL,
+  dismissed TINYINT(3) NOT NULL DEFAULT '0',
+  PRIMARY KEY(alarm_id,user_id)
+);
+
+CREATE INDEX ix_kolab_alarms_user_id ON kolab_alarms(user_id);
+
+CREATE TABLE itipinvitations (
+  token VARCHAR(64) NOT NULL PRIMARY KEY,
+  event_uid VARCHAR(255) NOT NULL,
+  user_id INTEGER NOT NULL DEFAULT '0',
+  event TEXT NOT NULL,
+  expires DATETIME DEFAULT NULL,
+  cancelled TINYINT(3) NOT NULL DEFAULT '0'
+);
+
+CREATE INDEX ix_itipinvitations_uid ON itipinvitations(event_uid,user_id);
+
+INSERT INTO system (name, value) VALUES ('calendar-caldav-version', '2014041700');