change column type of admission_seminar_uer.comment and seminar_user.comment, fixes #830

db/migrations/5.1.26_change_seminar_user_comment_type.php

+<?php
+final class ChangeSeminarUserCommentType extends Migration
+{
+    public function description()
+    {
+        return 'Changes the type of the comment column of tables seminar_user '
+             . 'and admission_seminar_user to VARCHAR(255) instead of TINYTEXT';
+    }
+
+    protected function up()
+    {
+        $query = "ALTER TABLE `admission_seminar_user`
+                  MODIFY COLUMN `comment` VARCHAR(255) NOT NULL DEFAULT ''";
+        DBManager::get()->exec($query);
+
+        $query = "ALTER TABLE `seminar_user`
+                  MODIFY COLUMN `comment` VARCHAR(255) NOT NULL DEFAULT ''";
+        DBManager::get()->exec($query);
+    }
+
+    protected function down()
+    {
+        // Column seminar_user does not need to be changed since it's already
+        // VARCHAR(255) in db/studip.sql
+
+        $query = "ALTER TABLE `admission_seminar_user`
+                  MODIFY COLUMN `comment` TINYTEXT";
+        DBManager::get()->exec($query);
+    }
+}