diff --git a/sql-schema/121.sql b/sql-schema/121.sql
new file mode 100644
index 0000000000..fc5646afd3
--- /dev/null
+++ b/sql-schema/121.sql
@@ -0,0 +1,8 @@
+DELETE FROM `sensors_to_state_indexes` WHERE `sensors_to_state_indexes`.`sensor_id` NOT IN (SELECT DISTINCT `sensors`.`sensor_id` FROM `sensors` INNER JOIN `devices` ON `sensors`.`device_id` = `devices`.`device_id`);
+DELETE FROM `sensors` WHERE `sensors`.`device_id` NOT IN (SELECT `device_id` FROM `devices`);
+DELETE FROM `state_indexes` WHERE `state_indexes`.`state_index_id` NOT IN (SELECT `sensors_to_state_indexes`.`state_index_id` FROM `sensors_to_state_indexes`);
+DELETE FROM `state_translations` WHERE `state_translations`.`state_index_id` NOT IN (SELECT `state_indexes`.`state_index_id` FROM `state_indexes`);
+
+ALTER TABLE `sensors` CHANGE `device_id` `device_id` INT(11) UNSIGNED NOT NULL DEFAULT '0';
+ALTER TABLE `sensors` ADD CONSTRAINT `sensors_device_id_foreign` FOREIGN KEY (`device_id`) REFERENCES `devices` (`device_id`) ON DELETE CASCADE;
+ALTER TABLE `sensors_to_state_indexes` ADD CONSTRAINT `sensors_to_state_indexes_sensor_id_foreign` FOREIGN KEY (`sensor_id`) REFERENCES `sensors` (`sensor_id`) ON DELETE CASCADE;
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