diff --git a/db/app_uoj233.sql b/db/app_uoj233.sql
index 558f426..0127874 100644
--- a/db/app_uoj233.sql
+++ b/db/app_uoj233.sql
@@ -692,7 +692,7 @@ CREATE TABLE `problems_solutions` (
   `problem_id` int NOT NULL,
   `blog_id` int NOT NULL,
   PRIMARY KEY (`problem_id`, `blog_id`),
-  UNIQUE KEY `blog_id` (`blog_id`),
+  UNIQUE KEY `unique__blog_id` (`blog_id`),
   KEY `problem_id` (`problem_id`)
 ) ENGINE=MyISAM DEFAULT CHARSET=utf8mb4;
 /*!40101 SET character_set_client = @saved_cs_client */;
@@ -987,7 +987,7 @@ UNLOCK TABLES;
 CREATE TABLE `user_info` (
   `usergroup` char(1) COLLATE utf8mb4_unicode_ci NOT NULL DEFAULT 'U',
   `username` varchar(20) COLLATE utf8mb4_unicode_ci NOT NULL,
-  `usertype` varchar(250) COLLATE utf8mb4_unicode_ci NOT NULL DEFAULT 'student',
+  `usertype` enum('student','teacher','system','banned') COLLATE utf8mb4_unicode_ci NOT NULL DEFAULT 'student',
   `realname` varchar(30) COLLATE utf8mb4_unicode_ci NOT NULL DEFAULT '',
   `school` varchar(50) COLLATE utf8mb4_unicode_ci NOT NULL DEFAULT '',
   `email` varchar(50) COLLATE utf8mb4_unicode_ci NOT NULL,
diff --git a/web/app/libs/uoj-utility-lib.php b/web/app/libs/uoj-utility-lib.php
index 2aa54c4..ad016ff 100644
--- a/web/app/libs/uoj-utility-lib.php
+++ b/web/app/libs/uoj-utility-lib.php
@@ -150,27 +150,6 @@ function camelize($str, $delimiters = '-_') {
 	return $str;
 }
 
-function addUserType(&$user, $type) {
-	$usertype = explode(',', $user['usertype']);
-	if (!in_array($type, $usertype)) {
-		$usertype[] = $type;
-	}
-	$user['usertype'] = implode(',', $usertype);
-	return $user;
-}
-function removeUserType(&$user, $type) {
-	$usertype = explode(',', $user['usertype']);
-	if (in_array($type, $usertype)) {
-		$usertype = array_diff($usertype, array($type));
-	}
-	$user['usertype'] = implode(',', $usertype);
-	return $user;
-}
-function hasUserType($user, $type) {
-	$usertype = explode(',', $user['usertype']);
-	return in_array($type, $usertype);
-}
-
 function isSuperUser($user) {
 	return $user != null && $user['usergroup'] == 'S';
 }
diff --git a/web/app/upgrade/18_user_permissions/up.sql b/web/app/upgrade/18_user_permissions/up.sql
new file mode 100644
index 0000000..6219d6c
--- /dev/null
+++ b/web/app/upgrade/18_user_permissions/up.sql
@@ -0,0 +1,2 @@
+ALTER TABLE `problems_solutions` ADD UNIQUE KEY `unique__blog_id` (`blog_id`);
+ALTER TABLE `user_info` MODIFY `usertype` enum('student','teacher','system','banned') COLLATE utf8mb4_unicode_ci NOT NULL DEFAULT 'student';
diff --git a/web/app/upgrade/18_user_permissions/upgrade.php b/web/app/upgrade/18_user_permissions/upgrade.php
new file mode 100644
index 0000000..b1796f9
--- /dev/null
+++ b/web/app/upgrade/18_user_permissions/upgrade.php
@@ -0,0 +1,69 @@
+<?php
+
+return function ($type) {
+	if ($type === 'up') {
+		DB::init();
+
+		$users = DB::selectAll("select * from user_info");
+
+		foreach ($users as $user) {
+			$usertype = explode(',', $user['usertype']);
+			$extra = UOJUser::getExtra($user);
+			$new_permissions = [
+				'_placeholder' => '',
+				'problems' => [
+					'_placeholder' => '',
+				],
+				'contests' => [
+					'_placeholder' => '',
+				],
+				'lists' => [
+					'_placeholder' => '',
+				],
+				'groups' => [
+					'_placeholder' => '',
+				],
+				'blogs' => [
+					'_placeholder' => '',
+				],
+				'users' => [
+					'_placeholder' => '',
+				]
+			];
+
+			if (in_array('problem_uploader', $usertype)) {
+				$new_permissions['problems']['create'] = true;
+			}
+
+			if (in_array('problem_manager', $usertype)) {
+				$new_permissions['problems']['create'] = true;
+				$new_permissions['problems']['manage'] = true;
+			}
+
+			if (in_array('contest_judger', $usertype)) {
+				$new_permissions['contests']['start_final_test'] = true;
+			}
+
+			if (in_array('teacher', $usertype)) {
+				$usertype = 'teacher';
+			} elseif (in_array('banned', $usertype)) {
+				$usertype = 'banned';
+			} else {
+				$usertype = 'student';
+			}
+
+			$extra['permissions'] = $new_permissions;
+
+			DB::update([
+				"update user_info",
+				"set", [
+					"usertype" => $usertype,
+					"extra" => json_encode($extra),
+				],
+				"where", [
+					"username" => $user['username'],
+				],
+			]);
+		}
+	}
+};