db: Allow DELETE FROM Devices, cascade Media and EventsCam

This is to get out of the tricky situation when removing a camera may
fail if a new Media or EventsCam record appeared during the removal.
Removal entails deleting recordings from the filesystem, which can take
substantial time, and we have actually got report of this problem.

misc/sql/installed_db_version

@@ -1 +1 @@
-3000012
+3010400

misc/sql/mysql-upgrade/3010400/delete-device-cascade.sh

@@ -0,0 +1,11 @@
+#!/bin/bash
+
+echo '
+ALTER TABLE EventsCam DROP CONSTRAINT `EventsCam_ibfk_3`;
+ALTER TABLE EventsCam ADD  CONSTRAINT `EventsCam_ibfk_3` FOREIGN KEY (`device_id`) REFERENCES `Devices` (`id`) ON UPDATE CASCADE ON DELETE CASCADE;
+
+ALTER TABLE Media     DROP CONSTRAINT `Media_ibfk_1`;
+ALTER TABLE Media     ADD  CONSTRAINT `Media_ibfk_1`     FOREIGN KEY (`device_id`) REFERENCES `Devices` (`id`) ON UPDATE CASCADE ON DELETE CASCADE;
+' | mysql -h"$host" -D"$dbname" -u"$user" -p"$password"
+
+exit 0

misc/sql/schema_mysql.sql

@@ -174,7 +174,7 @@ CREATE TABLE `EventsCam` (
   KEY `time_index` (`time`) USING BTREE,
   CONSTRAINT `EventsCam_ibfk_1` FOREIGN KEY (`media_id`) REFERENCES `Media` (`id`) ON DELETE CASCADE,
   CONSTRAINT `EventsCam_ibfk_2` FOREIGN KEY (`level_id`) REFERENCES `EventLevels` (`id`),
-  CONSTRAINT `EventsCam_ibfk_3` FOREIGN KEY (`device_id`) REFERENCES `Devices` (`id`) ON UPDATE CASCADE,
+  CONSTRAINT `EventsCam_ibfk_3` FOREIGN KEY (`device_id`) REFERENCES `Devices` (`id`) ON UPDATE CASCADE ON DELETE CASCADE,
   CONSTRAINT `EventsCam_ibfk_4` FOREIGN KEY (`type_id`) REFERENCES `EventTypesCam` (`id`)
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8;
 /*!40101 SET character_set_client = @saved_cs_client */;
@@ -227,7 +227,7 @@ CREATE TABLE `Media` (
   `archive` tinyint(1) NOT NULL DEFAULT '0',
   PRIMARY KEY (`id`),
   KEY `device_id` (`device_id`),
-  CONSTRAINT `Media_ibfk_1` FOREIGN KEY (`device_id`) REFERENCES `Devices` (`id`) ON UPDATE CASCADE
+  CONSTRAINT `Media_ibfk_1` FOREIGN KEY (`device_id`) REFERENCES `Devices` (`id`) ON UPDATE CASCADE ON DELETE CASCADE
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8;
 /*!40101 SET character_set_client = @saved_cs_client */;
 DROP TABLE IF EXISTS `OnvifEvents`;