add missing indices, fixes #4157

Closes #4157

Merge request studip/studip!2997

db/migrations/5.1.58_add_missing_indices_for_table_schedule_seminare.php

+<?php
+/**
+ * @see https://gitlab.studip.de/studip/studip/-/issues/4157
+ */
+return new class extends Migration
+{
+    public function description()
+    {
+        return 'Adds missing indices for columns "seminar_id" and "metadate_id" for table "schedule_seminare"';
+    }
+
+    protected function up()
+    {
+        $query = "ALTER TABLE `schedule_seminare`
+                  ADD INDEX `seminar_id` (`seminar_id`),
+                  ADD INDEX `metadate_id` (`metadate_id`)";
+        DBManager::get()->exec($query);
+    }
+
+    protected function down()
+    {
+        $query = "ALTER TABLE `schedule_seminare`
+                  DROP INDEX `seminar_id`,
+                  DROP INDEX `metadate_id`";
+        DBManager::get()->exec($query);
+    }
+};