diff --git a/sql-schema/097.sql b/sql-schema/097.sql
new file mode 100644
index 0000000000..a0a27c248a
--- /dev/null
+++ b/sql-schema/097.sql
@@ -0,0 +1,2 @@
+DELETE a1 FROM alerts a1, alerts a2 WHERE a1.id < a2.id AND a1.device_id = a2.device_id AND a1.rule_id = a2.rule_id;
+ALTER TABLE `alerts` ADD UNIQUE `unique_alert`(`device_id`, `rule_id`);