diff --git a/uoj/1/app/controllers/add_contest.php b/uoj/1/app/controllers/add_contest.php
index 2f90a84..381ab70 100644
--- a/uoj/1/app/controllers/add_contest.php
+++ b/uoj/1/app/controllers/add_contest.php
@@ -39,9 +39,9 @@
 		
 		$esc_name = $_POST['name'];
 		$esc_name = $purifier->purify($esc_name);
-		$esc_name = mysql_real_escape_string($esc_name);
+		$esc_name = DB::escape($esc_name);
 		
-		mysql_query("insert into contests (name, start_time, last_min, status) values ('$esc_name', '$start_time_str', ${_POST['last_min']}, 'unfinished')");
+		DB::query("insert into contests (name, start_time, last_min, status) values ('$esc_name', '$start_time_str', ${_POST['last_min']}, 'unfinished')");
 	};
 	$time_form->succ_href="/contests";
 	$time_form->runAtServer();
@@ -53,4 +53,4 @@
 	$time_form->printHTML();
 ?>
 </div>
-<?php echoUOJPageFooter() ?>
+<?php echoUOJPageFooter() ?>
\ No newline at end of file
diff --git a/uoj/1/app/controllers/change_user_info.php b/uoj/1/app/controllers/change_user_info.php
index 6bdb389..477754b 100644
--- a/uoj/1/app/controllers/change_user_info.php
+++ b/uoj/1/app/controllers/change_user_info.php
@@ -29,7 +29,7 @@
 		{
 			return "失败：无效电子邮箱。";
 		}
-		$esc_email = mysql_real_escape_string($email);
+		$esc_email = DB::escape($email);
 		DB::update("update user_info set email = '$esc_email' where username = '{$myUser['username']}'");
 
 		if ($_POST['Qtag'])
@@ -39,7 +39,7 @@
 			{
 				return "失败：无效QQ。";
 			}
-			$esc_qq = mysql_real_escape_string($qq);
+			$esc_qq = DB::escape($qq);
 			DB::update("update user_info set qq = '$esc_qq' where username = '{$myUser['username']}'");
 		}
 		else
@@ -47,7 +47,7 @@
 		if ($_POST['sex'] == "U" || $_POST['sex'] == 'M' || $_POST['sex'] == 'F')
 		{
 			$sex = $_POST['sex'];
-			$esc_sex = mysql_real_escape_string($sex);
+			$esc_sex = DB::escape($sex);
 			DB::update("update user_info set sex = '$esc_sex' where username = '{$myUser['username']}'");
 		}
 		
diff --git a/uoj/1/app/controllers/click_zan.php b/uoj/1/app/controllers/click_zan.php
index 45403f8..3b3058f 100644
--- a/uoj/1/app/controllers/click_zan.php
+++ b/uoj/1/app/controllers/click_zan.php
@@ -39,26 +39,26 @@
 	$cur = queryZanVal($id, $type, $myUser);
 	
 	if ($cur != $delta) {
-		$row = mysql_fetch_array(mysql_query("select zan from $table_name where id = $id"));
+		$row = DB::selectFirst("select zan from $table_name where id = $id");
 		if ($row == null) {
 			die('<div class="text-danger">failed</div>');
 		}
 		$cur += $delta;
 		if ($cur == 0) {
-			mysql_query("delete from click_zans where username = '{$myUser['username']}' and type = '$type' and target_id = $id");
+			DB::query("delete from click_zans where username = '{$myUser['username']}' and type = '$type' and target_id = $id");
 		} else if ($cur != $delta) {
-			mysql_query("update click_zans set val = '$cur' where username = '{$myUser['username']}' and type = '$type' and target_id = $id");
+			DB::query("update click_zans set val = '$cur' where username = '{$myUser['username']}' and type = '$type' and target_id = $id");
 		} else {
-			mysql_query("insert into click_zans (username, type, target_id, val) values ('{$myUser['username']}', '$type', $id, $cur)");
+			DB::query("insert into click_zans (username, type, target_id, val) values ('{$myUser['username']}', '$type', $id, $cur)");
 		}
 		$cnt = $row['zan'] + $delta;
-		mysql_query("update $table_name set zan = $cnt where id = $id");
+		DB::query("update $table_name set zan = $cnt where id = $id");
 	} else {
-		$row = mysql_fetch_array(mysql_query("select zan from $table_name where id = $id"));
+		$row = DB::selectFirst("select zan from $table_name where id = $id");
 		if ($row == null) {
 			die('<div class="text-danger">failed</div>');
 		}
 		$cnt = $row['zan'];
 	}
 ?>
-<?= getClickZanBlock($type, $id, $cnt, $cur) ?>
+<?= getClickZanBlock($type, $id, $cnt, $cur) ?>
\ No newline at end of file
diff --git a/uoj/1/app/controllers/contest_inside.php b/uoj/1/app/controllers/contest_inside.php
index ee54acd..fce485d 100644
--- a/uoj/1/app/controllers/contest_inside.php
+++ b/uoj/1/app/controllers/contest_inside.php
@@ -18,9 +18,9 @@
 	}
 
 	if (isset($_POST['check_notice'])) {
-		$result = mysql_query("select * from contests_notice where contest_id = '${contest['id']}' order by time desc limit 1");
+		$result = DB::query("select * from contests_notice where contest_id = '${contest['id']}' order by time desc limit 1");
 		try {
-			while ($row = mysql_fetch_array($result)) {
+			while ($row = DB::fetch($result)) {
 				if (new DateTime($row['time']) > new DateTime($_POST['last_time'])) {
 					die(json_encode(array('msg' => $row['title'] . ' : ' . $row['content'], 'time' => UOJTime::$time_now_str)));
 				}
@@ -44,18 +44,18 @@
 		$problems = array();
 		$prob_pos = array();
 		$n_problems = 0;
-		$result = mysql_query("select problem_id from contests_problems where contest_id = ${contest['id']} order by problem_id");
-		while ($row = mysql_fetch_array($result, MYSQL_NUM)) {
+		$result = DB::query("select problem_id from contests_problems where contest_id = ${contest['id']} order by problem_id");
+		while ($row = DB::fetch($result, MYSQLI_NUM)) {
 			$prob_pos[$problems[] = (int)$row[0]] = $n_problems++;
 		}
 		
 		$data = array();
 		if ($contest['cur_progress'] < CONTEST_FINISHED) {
-			$result = mysql_query("select id, submit_time, submitter, problem_id, score from submissions where contest_id = {$contest['id']} and score is not null order by id");
+			$result = DB::query("select id, submit_time, submitter, problem_id, score from submissions where contest_id = {$contest['id']} and score is not null order by id");
 		} else {
-			$result = mysql_query("select submission_id, date_add('{$contest['start_time_str']}', interval penalty second), submitter, problem_id, score from contests_submissions where contest_id = {$contest['id']}");
+			$result = DB::query("select submission_id, date_add('{$contest['start_time_str']}', interval penalty second), submitter, problem_id, score from contests_submissions where contest_id = {$contest['id']}");
 		}
-		while ($row = mysql_fetch_array($result, MYSQL_NUM)) {
+		while ($row = DB::fetch($result, MYSQLI_NUM)) {
 			$row[0] = (int)$row[0];
 			$row[3] = $prob_pos[$row[3]];
 			$row[4] = (int)$row[4];
@@ -63,8 +63,8 @@
 		}
 		
 		$people = array();
-		$result = mysql_query("select username, user_rating from contests_registrants where contest_id = {$contest['id']} and has_participated = 1");
-		while ($row = mysql_fetch_array($result, MYSQL_NUM)) {
+		$result = DB::query("select username, user_rating from contests_registrants where contest_id = {$contest['id']} and has_participated = 1");
+		while ($row = DB::fetch($result, MYSQLI_NUM)) {
 			$row[1] = (int)$row[1];
 			$people[] = $row;
 		}
@@ -137,8 +137,8 @@
 			$start_test_form = new UOJForm('start_test');
 			$start_test_form->handle = function() {
 				global $contest;
-				$result = mysql_query("select id, problem_id, content from submissions where contest_id = {$contest['id']}");
-				while ($submission = mysql_fetch_array($result, MYSQL_ASSOC)) {
+				$result = DB::query("select id, problem_id, content from submissions where contest_id = {$contest['id']}");
+				while ($submission = DB::fetch($result, MYSQLI_ASSOC)) {
 					if (!isset($contest['extra_config']["problem_{$submission['problem_id']}"])) {
 	 					$content = json_decode($submission['content'], true);
 						if (isset($content['final_test_config'])) {
@@ -148,11 +148,11 @@
 						if (isset($content['first_test_config'])) {
 							unset($content['first_test_config']);
 						}
-						$esc_content = mysql_real_escape_string(json_encode($content));
+						$esc_content = DB::escape(json_encode($content));
 						DB::update("update submissions set judge_time = NULL, result = '', score = NULL, status = 'Waiting Rejudge', content = '$esc_content' where id = {$submission['id']}");
 					}
 				}
-				mysql_query("update contests set status = 'testing' where id = {$contest['id']}");
+				DB::query("update contests set status = 'testing' where id = {$contest['id']}");
 			};
 			$start_test_form->submit_button_config['class_str'] = 'btn btn-danger btn-block';
 			$start_test_form->submit_button_config['smart_confirm'] = '';
@@ -202,10 +202,10 @@ EOD;
 EOD;
 					}
 					sendSystemMsg($user['username'], 'Rating变化通知', $content);
-					mysql_query("update user_info set rating = {$ratings[$i]} where username = '{$standings[$i][2][0]}'");
-					mysql_query("update contests_registrants set rank = {$standings[$i][3]} where contest_id = {$contest['id']} and username = '{$standings[$i][2][0]}'");
+					DB::query("update user_info set rating = {$ratings[$i]} where username = '{$standings[$i][2][0]}'");
+					DB::query("update contests_registrants set rank = {$standings[$i][3]} where contest_id = {$contest['id']} and username = '{$standings[$i][2][0]}'");
 				}
-				mysql_query("update contests set status = 'finished' where id = {$contest['id']}");
+				DB::query("update contests set status = 'finished' where id = {$contest['id']}");
 			};
 			$publish_result_form->submit_button_config['class_str'] = 'btn btn-danger btn-block';
 			$publish_result_form->submit_button_config['smart_confirm'] = '';
@@ -412,7 +412,7 @@ EOD;
 		global $contest;
 		$title = DB::escape($_POST['title']);
 		$content = DB::escape($_POST['content']);
-		mysql_query("insert into contests_notice (contest_id, title, content, time) values ('{$contest['id']}', '$title', '$content', now())");
+		DB::query("insert into contests_notice (contest_id, title, content, time) values ('{$contest['id']}', '$title', '$content', now())");
 	};
 	$post_notice->runAtServer();
 	
@@ -520,4 +520,4 @@ EOD;
 		<?php } ?>
 	</div>
 </div>
-<?php echoUOJPageFooter() ?>
+<?php echoUOJPageFooter() ?>
\ No newline at end of file
diff --git a/uoj/1/app/controllers/contest_manage.php b/uoj/1/app/controllers/contest_manage.php
index 9e07c9a..3949efd 100644
--- a/uoj/1/app/controllers/contest_manage.php
+++ b/uoj/1/app/controllers/contest_manage.php
@@ -60,9 +60,9 @@
 		function($type, $username) {
 			global $contest;
 			if ($type == '+') {
-				mysql_query("insert into contests_permissions (contest_id, username) values (${contest['id']}, '$username')");
+				DB::query("insert into contests_permissions (contest_id, username) values (${contest['id']}, '$username')");
 			} else if ($type == '-') {
-				mysql_query("delete from contests_permissions where contest_id = ${contest['id']} and username = '$username'");
+				DB::query("delete from contests_permissions where contest_id = ${contest['id']} and username = '$username'");
 			}
 		}
 	);
@@ -205,7 +205,7 @@
 <?php
 	$row_id = 0;
 	$result = DB::query("select username from contests_permissions where contest_id = {$contest['id']}");
-	while ($row = mysql_fetch_array($result, MYSQL_ASSOC)) {
+	while ($row = DB::fetch($result, MYSQLI_ASSOC)) {
 		$row_id++;
 		echo '<tr>', '<td>', $row_id, '</td>', '<td>', getUserLink($row['username']), '</td>', '</tr>';
 	}
@@ -227,7 +227,7 @@
 			<tbody>
 <?php
 	$result = DB::query("select problem_id from contests_problems where contest_id = ${contest['id']} order by problem_id asc");
-	while ($row = mysql_fetch_array($result, MYSQL_ASSOC)) {
+	while ($row = DB::fetch($result, MYSQLI_ASSOC)) {
 		$problem = queryProblemBrief($row['problem_id']);
 		$problem_config_str = isset($contest['extra_config']["problem_{$problem['id']}"]) ? $contest['extra_config']["problem_{$problem['id']}"] : 'sample';
 		echo '<tr>', '<td>', $problem['id'], '</td>', '<td>', getProblemLink($problem), ' ', "[$problem_config_str]", '</td>', '</tr>';
@@ -259,4 +259,4 @@
 	</div>
 	<?php endif ?>
 </div>
-<?php echoUOJPageFooter() ?>
+<?php echoUOJPageFooter() ?>
\ No newline at end of file
diff --git a/uoj/1/app/controllers/contest_members.php b/uoj/1/app/controllers/contest_members.php
index 4a4407f..6de75e2 100644
--- a/uoj/1/app/controllers/contest_members.php
+++ b/uoj/1/app/controllers/contest_members.php
@@ -16,7 +16,7 @@
 			$unregister_form = new UOJForm('unregister');
 			$unregister_form->handle = function() {
 				global $myUser, $contest;
-				mysql_query("delete from contests_registrants where username = '{$myUser['username']}' and contest_id = {$contest['id']}");
+				DB::query("delete from contests_registrants where username = '{$myUser['username']}' and contest_id = {$contest['id']}");
 				updateContestPlayerNum($contest);
 			};
 			$unregister_form->submit_button_config['class_str'] = 'btn btn-danger btn-xs';
@@ -108,4 +108,4 @@
 		)
 	);
 ?>
-<?php echoUOJPageFooter() ?>
+<?php echoUOJPageFooter() ?>
\ No newline at end of file
diff --git a/uoj/1/app/controllers/contest_registration.php b/uoj/1/app/controllers/contest_registration.php
index 5206019..99c1a16 100644
--- a/uoj/1/app/controllers/contest_registration.php
+++ b/uoj/1/app/controllers/contest_registration.php
@@ -14,7 +14,7 @@
 	$register_form = new UOJForm('register');
 	$register_form->handle = function() {
 		global $myUser, $contest;
-		mysql_query("insert into contests_registrants (username, user_rating, contest_id, has_participated) values ('{$myUser['username']}', {$myUser['rating']}, {$contest['id']}, 0)");
+		DB::query("insert into contests_registrants (username, user_rating, contest_id, has_participated) values ('{$myUser['username']}', {$myUser['rating']}, {$contest['id']}, 0)");
 		updateContestPlayerNum($contest);
 	};
 	$register_form->submit_button_config['class_str'] = 'btn btn-primary';
diff --git a/uoj/1/app/controllers/download.php b/uoj/1/app/controllers/download.php
index bf44d94..9ddf720 100644
--- a/uoj/1/app/controllers/download.php
+++ b/uoj/1/app/controllers/download.php
@@ -8,8 +8,8 @@
 			
 			$visible = isProblemVisibleToUser($problem, $myUser);
 			if (!$visible && $myUser != null) {
-				$result = mysql_query("select contest_id from contests_problems where problem_id = {$_GET['id']}");
-				while (list($contest_id) = mysql_fetch_array($result, MYSQL_NUM)) {
+				$result = DB::query("select contest_id from contests_problems where problem_id = {$_GET['id']}");
+				while (list($contest_id) = DB::fetch($result, MYSQLI_NUM)) {
 					$contest = queryContest($contest_id);
 					genMoreContestInfo($contest);
 					if ($contest['cur_progress'] != CONTEST_NOT_STARTED && hasRegistered($myUser, $contest) && queryContestProblemRank($contest, $problem)) {
@@ -44,4 +44,4 @@
 	header("X-Sendfile: $file_name");
 	header("Content-type: $mimetype");
 	header("Content-Disposition: attachment; filename=$download_name");
-?>
+?>
\ No newline at end of file
diff --git a/uoj/1/app/controllers/hack.php b/uoj/1/app/controllers/hack.php
index 29fc0ac..27ff28e 100644
--- a/uoj/1/app/controllers/hack.php
+++ b/uoj/1/app/controllers/hack.php
@@ -23,7 +23,7 @@
 		$delete_form = new UOJForm('delete');
 		$delete_form->handle = function() {
 			global $hack;
-			mysql_query("delete from hacks where id = {$hack['id']}");
+			DB::query("delete from hacks where id = {$hack['id']}");
 		};
 		$delete_form->submit_button_config['class_str'] = 'btn btn-danger';
 		$delete_form->submit_button_config['text'] = '删除此Hack';
diff --git a/uoj/1/app/controllers/judge/submit.php b/uoj/1/app/controllers/judge/submit.php
index 3016ed8..480bf79 100644
--- a/uoj/1/app/controllers/judge/submit.php
+++ b/uoj/1/app/controllers/judge/submit.php
@@ -42,7 +42,7 @@
 				$content['first_test_config'] = $content['config'];
 				$content['config'] = $content['final_test_config'];
 				unset($content['final_test_config']);
-				$esc_content = mysql_real_escape_string(json_encode($content));
+				$esc_content = DB::escape(json_encode($content));
 			
 				DB::update("update submissions set status = 'Judged, Waiting', content = '$esc_content' where id = ${_POST['id']}");
 			}
@@ -77,11 +77,11 @@
 		$ok = DB::update("update hacks set success = {$result['score']}, details = '$esc_details' where id = {$_POST['id']}");
 		
 		if ($ok) {
-			list($hack_input) = mysql_fetch_array(mysql_query("select input from hacks where id = {$_POST['id']}"), MYSQL_NUM);
+			list($hack_input) = DB::fetch(DB::query("select input from hacks where id = {$_POST['id']}"), MYSQLI_NUM);
 			unlink(UOJContext::storagePath().$hack_input);
 
 			if ($result['score']) {
-				list($problem_id) = mysql_fetch_array(mysql_query("select problem_id from hacks where id = ${_POST['id']}"), MYSQL_NUM);
+				list($problem_id) = DB::selectFirst("select problem_id from hacks where id = ${_POST['id']}", MYSQLI_NUM);
 				if (validateUploadedFile('hack_input') && validateUploadedFile('std_output')) {
 					svnAddExtraTest(queryProblemBrief($problem_id), $_FILES["hack_input"]["tmp_name"], $_FILES["std_output"]["tmp_name"]);
 				} else {
@@ -209,4 +209,4 @@
 	}
 	
 	echo json_encode($submission);
-?>
+?>
\ No newline at end of file
diff --git a/uoj/1/app/controllers/problem.php b/uoj/1/app/controllers/problem.php
index f5c1ecb..8544a9b 100644
--- a/uoj/1/app/controllers/problem.php
+++ b/uoj/1/app/controllers/problem.php
@@ -110,9 +110,9 @@
 		$result_json = json_encode($result);
 		
 		if ($is_in_contest) {
-			mysql_query("insert into submissions (problem_id, contest_id, submit_time, submitter, content, language, tot_size, status, result, is_hidden) values (${problem['id']}, ${contest['id']}, now(), '${myUser['username']}', '$esc_content', '$esc_language', $tot_size, '${result['status']}', '$result_json', 0)");
+			DB::query("insert into submissions (problem_id, contest_id, submit_time, submitter, content, language, tot_size, status, result, is_hidden) values (${problem['id']}, ${contest['id']}, now(), '${myUser['username']}', '$esc_content', '$esc_language', $tot_size, '${result['status']}', '$result_json', 0)");
 		} else {
-			mysql_query("insert into submissions (problem_id, submit_time, submitter, content, language, tot_size, status, result, is_hidden) values (${problem['id']}, now(), '${myUser['username']}', '$esc_content', '$esc_language', $tot_size, '${result['status']}', '$result_json', {$problem['is_hidden']})");
+			DB::query("insert into submissions (problem_id, submit_time, submitter, content, language, tot_size, status, result, is_hidden) values (${problem['id']}, now(), '${myUser['username']}', '$esc_content', '$esc_language', $tot_size, '${result['status']}', '$result_json', {$problem['is_hidden']})");
 		}
  	}
 	function handleCustomTestUpload($zip_file_name, $content, $tot_size) {
@@ -262,4 +262,4 @@ $('#contest-countdown').countdown(<?= $contest['end_time']->getTimestamp() - UOJ
 	</div>
 	<?php endif ?>
 </div>
-<?php echoUOJPageFooter() ?>
+<?php echoUOJPageFooter() ?>
\ No newline at end of file
diff --git a/uoj/1/app/controllers/problem_data_manage.php b/uoj/1/app/controllers/problem_data_manage.php
index c84b2d4..c6fadba 100644
--- a/uoj/1/app/controllers/problem_data_manage.php
+++ b/uoj/1/app/controllers/problem_data_manage.php
@@ -526,7 +526,7 @@ EOD
 		}
 		
 		$hackable = $problem['hackable'] ? 1 : 0;
-		mysql_query("update problems set hackable = $hackable where id = ${problem['id']}");
+		DB::query("update problems set hackable = $hackable where id = ${problem['id']}");
 	};
 	$hackable_form->submit_button_config['class_str'] = 'btn btn-warning btn-block';
 	$hackable_form->submit_button_config['text'] = $problem['hackable'] ? '禁止使用hack' : '允许使用hack';
@@ -598,7 +598,7 @@ EOD
 		$config['view_all_details_type'] = $_POST['view_all_details_type'];
 		$config['view_details_type'] = $_POST['view_details_type'];
 		$esc_config = DB::escape(json_encode($config));
-		mysql_query("update problems set extra_config = '$esc_config' where id = '{$problem['id']}'");
+		DB::query("update problems set extra_config = '$esc_config' where id = '{$problem['id']}'");
 	};
 	$view_type_form->submit_button_config['class_str'] = 'btn btn-warning btn-block top-buffer-sm';
 	
diff --git a/uoj/1/app/controllers/problem_managers_manage.php b/uoj/1/app/controllers/problem_managers_manage.php
index 970e930..1cd9bb1 100644
--- a/uoj/1/app/controllers/problem_managers_manage.php
+++ b/uoj/1/app/controllers/problem_managers_manage.php
@@ -19,9 +19,9 @@
 		function($type, $username) {
 			global $problem;
 			if ($type == '+') {
-				mysql_query("insert into problems_permissions (problem_id, username) values (${problem['id']}, '$username')");
+				DB::query("insert into problems_permissions (problem_id, username) values (${problem['id']}, '$username')");
 			} else if ($type == '-') {
-				mysql_query("delete from problems_permissions where problem_id = ${problem['id']} and username = '$username'");
+				DB::query("delete from problems_permissions where problem_id = ${problem['id']} and username = '$username'");
 			}
 		},
 		function() {
@@ -51,8 +51,8 @@
 	<tbody>
 <?php
 	$row_id = 0;
-	$result = mysql_query("select username from problems_permissions where problem_id = ${problem['id']}");
-	while ($row = mysql_fetch_array($result, MYSQL_ASSOC)) {
+	$result = DB::query("select username from problems_permissions where problem_id = ${problem['id']}");
+	while ($row = DB::fetch($result, MYSQLI_ASSOC)) {
 		$row_id++;
 		echo '<tr>', '<td>', $row_id, '</td>', '<td>', getUserLink($row['username']), '</td>', '</tr>';
 	}
diff --git a/uoj/1/app/controllers/problem_set.php b/uoj/1/app/controllers/problem_set.php
index 583ad39..e18716e 100644
--- a/uoj/1/app/controllers/problem_set.php
+++ b/uoj/1/app/controllers/problem_set.php
@@ -6,9 +6,9 @@
 	if (isSuperUser($myUser)) {
 		$new_problem_form = new UOJForm('new_problem');
 		$new_problem_form->handle = function() {
-			mysql_query("insert into problems (title, is_hidden, submission_requirement) values ('New Problem', 1, '{}')");
-			$id = mysql_insert_id();
-			mysql_query("insert into problems_contents (id, statement, statement_md) values ($id, '', '')");
+			DB::query("insert into problems (title, is_hidden, submission_requirement) values ('New Problem', 1, '{}')");
+			$id = DB::insert_id();
+			DB::query("insert into problems_contents (id, statement, statement_md) values ($id, '', '')");
 			svnNewProblem($id);
 		};
 		$new_problem_form->submit_button_config['align'] = 'right';
diff --git a/uoj/1/app/controllers/problem_statistics.php b/uoj/1/app/controllers/problem_statistics.php
index 3c4a724..b6acce9 100644
--- a/uoj/1/app/controllers/problem_statistics.php
+++ b/uoj/1/app/controllers/problem_statistics.php
@@ -21,7 +21,7 @@
 		$is_res_empty = true;
 		$has_score_0 = false;
 		$has_score_100 = false;
-		while ($row = mysql_fetch_array($result, MYSQL_NUM)) {
+		while ($row = DB::fetch($result, MYSQLI_NUM)) {
 			if ($row[0] == 0) {
 				$has_score_0 = true;
 			} else if ($row[0] == 100) {
diff --git a/uoj/1/app/controllers/register.php b/uoj/1/app/controllers/register.php
index c637fe1..dc0ac69 100644
--- a/uoj/1/app/controllers/register.php
+++ b/uoj/1/app/controllers/register.php
@@ -35,9 +35,9 @@
 		
 		$svn_pw = uojRandString(10);
 		if (!DB::selectCount("SELECT COUNT(*) FROM user_info"))
-			mysql_query("insert into user_info (username, email, password, svn_password, register_time, usergroup) values ('$username', '$esc_email', '$password', '$svn_pw', now(), 'S')");
+			DB::query("insert into user_info (username, email, password, svn_password, register_time, usergroup) values ('$username', '$esc_email', '$password', '$svn_pw', now(), 'S')");
 		else
-			mysql_query("insert into user_info (username, email, password, svn_password, register_time) values ('$username', '$esc_email', '$password', '$svn_pw', now())");
+			DB::query("insert into user_info (username, email, password, svn_password, register_time) values ('$username', '$esc_email', '$password', '$svn_pw', now())");
 		
 		return "欢迎你！" . $username . "，你已成功注册。";
 	}
diff --git a/uoj/1/app/controllers/submissions_list.php b/uoj/1/app/controllers/submissions_list.php
index dca32da..990f4a2 100644
--- a/uoj/1/app/controllers/submissions_list.php
+++ b/uoj/1/app/controllers/submissions_list.php
@@ -19,7 +19,7 @@
 		$conds[] = "score <= $q_max_score";
 	}
 	if ($q_language != null) {
-		$conds[] = sprintf("language = '%s'", mysql_real_escape_string($q_language));
+		$conds[] = sprintf("language = '%s'", DB::escape($q_language));
 	}
 	
 	$html_esc_q_language = htmlspecialchars($q_language);
diff --git a/uoj/1/app/controllers/super_manage.php b/uoj/1/app/controllers/super_manage.php
index 035c43c..8d57052 100644
--- a/uoj/1/app/controllers/super_manage.php
+++ b/uoj/1/app/controllers/super_manage.php
@@ -74,7 +74,7 @@
 	$blog_link_contests->handle = function() {
 		$blog_id = $_POST['blog_id'];
 		$contest_id = $_POST['contest_id'];
-		$str = mysql_fetch_array(mysql_query("select * from contests where id='${contest_id}'"));
+		$str = DB::selectFirst(("select * from contests where id='${contest_id}'"));
 		$all_config = json_decode($str['extra_config'], true);
 		$config = $all_config['links'];
 
@@ -97,8 +97,8 @@
 
 		$all_config['links'] = $config;
 		$str = json_encode($all_config);
-		$str = mysql_real_escape_string($str);
-		mysql_query("update contests set extra_config='${str}' where id='${contest_id}'");
+		$str = DB::escape($str);
+		DB::query("update contests set extra_config='${str}' where id='${contest_id}'");
 	};
 	$blog_link_contests->runAtServer();
 	
diff --git a/uoj/1/app/controllers/user_info.php b/uoj/1/app/controllers/user_info.php
index f4c6cb6..d6b2147 100644
--- a/uoj/1/app/controllers/user_info.php
+++ b/uoj/1/app/controllers/user_info.php
@@ -107,10 +107,10 @@
 var rating_data = [[
 <?php
 	$user_rating_min = $user_rating_max = 1500;
-	$result = mysql_query("select contest_id, rank, user_rating from contests_registrants where username = '{$user['username']}' and has_participated = 1 order by contest_id");
+	$result = DB::query("select contest_id, rank, user_rating from contests_registrants where username = '{$user['username']}' and has_participated = 1 order by contest_id");
 	$is_first_row = true;
 	$last_rating = 1500;
-	while ($row = mysql_fetch_array($result)) {
+	while ($row = DB::fetch($result)) {
 		$contest = queryContest($row['contest_id']);
 		$rating_delta = $row['user_rating'] - $last_rating;
 		if (!$is_first_row) {
diff --git a/uoj/1/app/controllers/user_msg.php b/uoj/1/app/controllers/user_msg.php
index 1678182..4d272d7 100644
--- a/uoj/1/app/controllers/user_msg.php
+++ b/uoj/1/app/controllers/user_msg.php
@@ -15,23 +15,23 @@
 				return 'fail';
 			}
 			$receiver = $_POST['receiver'];
-			$esc_message = mysql_real_escape_string($_POST['message']);
+			$esc_message = DB::escape($_POST['message']);
 			$sender = $myUser['username'];
 
 			if (!validateUsername($receiver) || !queryUser($receiver)) {
 				return 'fail';
 			}
 
-			mysql_query("insert into user_msg (sender, receiver, message, send_time) values ('$sender', '$receiver', '$esc_message', now())");
+			DB::query("insert into user_msg (sender, receiver, message, send_time) values ('$sender', '$receiver', '$esc_message', now())");
 			return "ok";
 	}
 
 	function getConversations() {
 			global $myUser;
 			$username = $myUser['username'];
-			$result = mysql_query( "select * from user_msg where sender = '$username' or receiver = '$username' order by send_time DESC" );
+			$result = DB::query( "select * from user_msg where sender = '$username' or receiver = '$username' order by send_time DESC" );
 			$ret = array();
-			while ($msg = mysql_fetch_array($result)) {
+			while ($msg = DB::fetch($result)) {
 					if ($msg['sender'] !== $username) {
 							if (isset($ret[$msg['sender']])) {
 									$ret[$msg['sender']][1] |= ($msg['read_time'] == null);
@@ -63,11 +63,11 @@
 
 		$conversationName = $_GET['conversationName'];
 		$pageNumber = ($_GET['pageNumber'] - 1) * 10;
-		mysql_query("update user_msg set read_time = now() where sender = '$conversationName'  and  receiver = '$username' and read_time is null");
+		DB::query("update user_msg set read_time = now() where sender = '$conversationName'  and  receiver = '$username' and read_time is null");
 
-		$result = mysql_query("select * from user_msg where (sender = '$username' and receiver = '$conversationName') or (sender = '$conversationName' and receiver = '$username')	order by send_time DESC limit $pageNumber, 11");
+		$result = DB::query("select * from user_msg where (sender = '$username' and receiver = '$conversationName') or (sender = '$conversationName' and receiver = '$username')	order by send_time DESC limit $pageNumber, 11");
 		$ret = array();
-		while ($msg = mysql_fetch_array($result)) {
+		while ($msg = DB::fetch($result)) {
 			$ret[] = array($msg['message'], $msg['send_time'], $msg['read_time'], $msg['id'], ($msg['sender'] == $username));
 		}
 		return json_encode($ret);
@@ -81,13 +81,13 @@ select * from user_msg
 where id = $msgId
 and read_time is null
 EOD;
-    $result = mysql_query($str);
-    if (mysql_fetch_array($result)) {
+    $result = DB::query($str);
+    if (DB::fetch($result)) {
         $str = <<<EOD
 delete from user_msg
 where id = $msgId
 EOD;
-        mysql_query($str);
+        DB::query($str);
         return 1;
     }
     return 0;
diff --git a/uoj/1/app/libs/uoj-judger-lib.php b/uoj/1/app/libs/uoj-judger-lib.php
index bcad58a..97dcac6 100644
--- a/uoj/1/app/libs/uoj-judger-lib.php
+++ b/uoj/1/app/libs/uoj-judger-lib.php
@@ -159,13 +159,13 @@
 	}
 	
 	function rejudgeProblem($problem) {
-		mysql_query("update submissions set judge_time = NULL , result = '' , score = NULL , status = 'Waiting Rejudge' where problem_id = ${problem['id']}");
+		DB::query("update submissions set judge_time = NULL , result = '' , score = NULL , status = 'Waiting Rejudge' where problem_id = ${problem['id']}");
 	}
 	function rejudgeProblemAC($problem) {
-		mysql_query("update submissions set judge_time = NULL , result = '' , score = NULL , status = 'Waiting Rejudge' where problem_id = ${problem['id']} and score = 100");
+		DB::query("update submissions set judge_time = NULL , result = '' , score = NULL , status = 'Waiting Rejudge' where problem_id = ${problem['id']} and score = 100");
 	}
 	function rejudgeSubmission($submission) {
-		mysql_query("update submissions set judge_time = NULL , result = '' , score = NULL , status = 'Waiting Rejudge' where id = ${submission['id']}");
+		DB::query("update submissions set judge_time = NULL , result = '' , score = NULL , status = 'Waiting Rejudge' where id = ${submission['id']}");
 	}
 	function updateBestACSubmissions($username, $problem_id) {
 		$best = DB::selectFirst("select id, used_time, used_memory, tot_size from submissions where submitter = '$username' and problem_id = $problem_id and score = 100 order by used_time, used_memory, tot_size asc limit 1");
diff --git a/uoj/1/app/libs/uoj-query-lib.php b/uoj/1/app/libs/uoj-query-lib.php
index 774acbb..73b3b89 100644
--- a/uoj/1/app/libs/uoj-query-lib.php
+++ b/uoj/1/app/libs/uoj-query-lib.php
@@ -30,29 +30,29 @@ function hasContestPermission($user, $contest) {
 }
 
 function hasRegistered($user, $contest) {
-	return mysql_fetch_array(mysql_query("select * from contests_registrants where username = '${user['username']}' and contest_id = ${contest['id']}")) != null;
+	return DB::selectFirst("select * from contests_registrants where username = '${user['username']}' and contest_id = ${contest['id']}") != null;
 	}
 function hasAC($user, $problem) {
-	return mysql_fetch_array(mysql_query("select * from best_ac_submissions where submitter = '${user['username']}' and problem_id = ${problem['id']}")) != null;
+	return DB::selectFirst("select * from best_ac_submissions where submitter = '${user['username']}' and problem_id = ${problem['id']}") != null;
 }
 
 function queryUser($username) {
 	if (!validateUsername($username)) {
 		return null;
 	}
-	return DB::selectFirst("select * from user_info where username='$username'", MYSQL_ASSOC);
+	return DB::selectFirst("select * from user_info where username='$username'", MYSQLI_ASSOC);
 }
 function queryProblemContent($id) {
-	return mysql_fetch_array(mysql_query("select * from problems_contents where id = $id"), MYSQL_ASSOC);
+	return DB::selectFirst("select * from problems_contents where id = $id", MYSQLI_ASSOC);
 }
 function queryProblemBrief($id) {
-	return mysql_fetch_array(mysql_query("select * from problems where id = $id"), MYSQL_ASSOC);
+	return DB::selectFirst("select * from problems where id = $id", MYSQLI_ASSOC);
 }
 
 function queryProblemTags($id) {
 	$tags = array();
-	$result = mysql_query("select tag from problems_tags where problem_id = $id order by id");
-	while ($row = mysql_fetch_array($result, MYSQL_NUM)) {
+	$result = DB::query("select tag from problems_tags where problem_id = $id order by id");
+	while ($row = DB::fetch($result, MYSQLI_NUM)) {
 		$tags[] = $row[0];
 	}
 	return $tags;
@@ -64,24 +64,24 @@ function queryContestProblemRank($contest, $problem) {
 	return DB::selectCount("select count(*) from contests_problems where contest_id = {$contest['id']} and problem_id <= {$problem['id']}");
 }
 function querySubmission($id) {
-	return mysql_fetch_array(mysql_query("select * from submissions where id = $id"), MYSQL_ASSOC);
+	return DB::selectFirst("select * from submissions where id = $id", MYSQLI_ASSOC);
 }
 function queryHack($id) {
-	return mysql_fetch_array(mysql_query("select * from hacks where id = $id"), MYSQL_ASSOC);
+	return DB::selectFirst("select * from hacks where id = $id", MYSQLI_ASSOC);
 }
 function queryContest($id) {
-	return mysql_fetch_array(mysql_query("select * from contests where id = $id"), MYSQL_ASSOC);
+	return DB::selectFirst("select * from contests where id = $id", MYSQLI_ASSOC);
 }
 function queryContestProblem($id) {
-	return mysql_fetch_array(mysql_query("select * from contest_problems where contest_id = $id"), MYSQL_ASSOC);
+	return DB::selectFirst("select * from contest_problems where contest_id = $id", MYSQLI_ASSOC);
 }
 
 function queryZanVal($id, $type, $user) {
 	if ($user == null) {
 		return 0;
 	}
-	$esc_type = mysql_real_escape_string($type);
-	$row = mysql_fetch_array(mysql_query("select val from click_zans where username='{$user['username']}' and type='$esc_type' and target_id='$id'"));
+	$esc_type = DB::escape($type);
+	$row = DB::selectFirst("select val from click_zans where username='{$user['username']}' and type='$esc_type' and target_id='$id'");
 	if ($row == null) {
 		return 0;
 	}
@@ -89,18 +89,18 @@ function queryZanVal($id, $type, $user) {
 }
 
 function queryBlog($id) {
-	return mysql_fetch_array(mysql_query("select * from blogs where id='$id'"), MYSQL_ASSOC);
+	return DB::selectFirst("select * from blogs where id='$id'", MYSQLI_ASSOC);
 }
 function queryBlogTags($id) {
 	$tags = array();
 	$result = DB::select("select tag from blogs_tags where blog_id = $id order by id");
-	while ($row = DB::fetch($result, MYSQL_NUM)) {
+	while ($row = DB::fetch($result, MYSQLI_NUM)) {
 		$tags[] = $row[0];
 	}
 	return $tags;
 }
 function queryBlogComment($id) {
-	return mysql_fetch_array(mysql_query("select * from blogs_comments where id='$id'"), MYSQL_ASSOC);
+	return DB::selectFirst("select * from blogs_comments where id='$id'", MYSQLI_ASSOC);
 }
 
 function isProblemVisibleToUser($problem, $user) {
@@ -175,4 +175,4 @@ function deleteBlog($id) {
 	DB::delete("delete from blogs_comments where blog_id = $id");
 	DB::delete("delete from important_blogs where blog_id = $id");
 	DB::delete("delete from blogs_tags where blog_id = $id");
-}
+}
\ No newline at end of file
diff --git a/uoj/1/app/libs/uoj-svn-lib.php b/uoj/1/app/libs/uoj-svn-lib.php
index cf141ea..db1f05c 100644
--- a/uoj/1/app/libs/uoj-svn-lib.php
+++ b/uoj/1/app/libs/uoj-svn-lib.php
@@ -9,10 +9,10 @@
 		exec("cd /var/uoj_data; rm $id.zip; zip $id.zip $id -r -q");
 	}
 	function svnRefreshPasswordOfProblem($id) {
-		$result = mysql_query("select user_info.username, svn_password from problems_permissions, user_info where problem_id = $id and user_info.username = problems_permissions.username");
+		$result = DB::query("select user_info.username, svn_password from problems_permissions, user_info where problem_id = $id and user_info.username = problems_permissions.username");
 		$content = "[users]\n";
 		$content .= UOJConfig::$data['svn']['our-root']['username']." = ".UOJConfig::$data['svn']['our-root']['password']."\n";
-		while ($row = mysql_fetch_array($result, MYSQL_NUM)) {
+		while ($row = DB::fetch($result, MYSQLI_NUM)) {
 			$content .= "${row[0]} = ${row[1]}\n";
 		}
 		file_put_contents("/var/svn/problem/$id/conf/passwd", $content);
diff --git a/uoj/1/app/models/DB.php b/uoj/1/app/models/DB.php
index 9ed6e66..a6b7426 100644
--- a/uoj/1/app/models/DB.php
+++ b/uoj/1/app/models/DB.php
@@ -3,63 +3,81 @@
 class DB {
 	public static function init() {
 		global $uojMySQL;
-		@$uojMySQL = mysql_connect(UOJConfig::$data['database']['host'] . ':3306', UOJConfig::$data['database']['username'], UOJConfig::$data['database']['password']);
+		$uojMySQL = new mysqli(UOJConfig::$data['database']['host'] . ':3306', UOJConfig::$data['database']['username'], UOJConfig::$data['database']['password'], UOJConfig::$data['database']['database']);
+		if($uojMySQL == null){
+			echo '-----------------------\n';
+			echo $uojMySQL->connect_errno;
+			echo '========================\n';
+		}
 		if (!$uojMySQL) {
-			echo 'There is something wrong with database >_<.... ' . mysql_error();
+			echo 'There is something wrong with database >_<.... ' . mysqli_error($uojMySQL);
 			die();
 		}
-		mysql_select_db(UOJConfig::$data['database']['database']);
 	}
 	public static function escape($str) {
-		return mysql_real_escape_string($str);
+		global $uojMySQL;
+		return mysqli_real_escape_string($uojMySQL, $str);
 	}
-	public static function fetch($r, $opt = MYSQL_ASSOC) {
-		return mysql_fetch_array($r, $opt);
+	public static function fetch($r, $opt = MYSQLI_ASSOC) {
+		global $uojMySQL;
+		return mysqli_fetch_array($r, $opt);
 	}
 	
 	public static function query($q) {
-		return mysql_query($q);
+		global $uojMySQL;
+		return mysqli_query($uojMySQL, $q);
 	}
 	public static function update($q) {
-		return mysql_query($q);
+		global $uojMySQL;
+		return mysqli_query($uojMySQL, $q);
 	}
 	public static function insert($q) {
-		return mysql_query($q);
+		global $uojMySQL;
+		return mysqli_query($uojMySQL, $q);
 	}
 	public static function insert_id() {
-		return mysql_insert_id();
+		global $uojMySQL;
+		return mysqli_insert_id($uojMySQL);
 	}
 		
 	public static function delete($q) {
-		return mysql_query($q);
+		global $uojMySQL;
+		return mysqli_query($uojMySQL, $q);
 	}
 	public static function select($q) {
-		return mysql_query($q);
+		global $uojMySQL;
+		return mysqli_query($uojMySQL, $q);
 	}
-	public static function selectAll($q, $opt = MYSQL_ASSOC) {
+	public static function selectAll($q, $opt = MYSQLI_ASSOC) {
+		global $uojMySQL;
 		$res = array();
-		$qr = mysql_query($q);
-		while ($row = mysql_fetch_array($qr, $opt)) {
+		$qr = mysqli_query($uojMySQL, $q);
+		while ($row = mysqli_fetch_array($qr, $opt)) {
 			$res[] = $row;
 		}
 		return $res;
 	}
-	public static function selectFirst($q, $opt = MYSQL_ASSOC) {
-		return mysql_fetch_array(mysql_query($q), $opt);
+	public static function selectFirst($q, $opt = MYSQLI_ASSOC) {
+		global $uojMySQL;
+		return mysqli_fetch_array(mysqli_query($uojMySQL, $q), $opt);
 	}
 	public static function selectCount($q) {
-		list($cnt) = mysql_fetch_array(mysql_query($q), MYSQL_NUM);
+		global $uojMySQL;
+		list($cnt) = mysqli_fetch_array(mysqli_query($uojMySQL, $q), MYSQLI_NUM);
 		return $cnt;
 	}
 	
 	public static function checkTableExists($name) {
+		global $uojMySQL;
 		return DB::query("select 1 from $name") !== false;
 	}
 	
 	public static function num_rows() {
-		return mysql_num_rows();
+		global $uojMySQL;
+		return mysqli_num_rows($uojMySQL);
 	}
 	public static function affected_rows() {
-		return mysql_affected_rows();
+		global $uojMySQL;
+		return mysqli_affected_rows($uojMySQL);
 	}
-}
+}
\ No newline at end of file
diff --git a/uoj/1/app/vendor/phpmailer/docs/extending.html b/uoj/1/app/vendor/phpmailer/docs/extending.html
index ec2b851..4126846 100644
--- a/uoj/1/app/vendor/phpmailer/docs/extending.html
+++ b/uoj/1/app/vendor/phpmailer/docs/extending.html
@@ -23,12 +23,11 @@ $mail->FromName = 'List manager';
 $mail->Host     = 'smtp1.example.com;smtp2.example.com';
 $mail->Mailer   = 'smtp';
 
-@mysqli_connect('localhost','root','password');
-@mysqli_select_db("my_company");
+@$mm = new mysqli('localhost','root','password', 'my_company');
 $query = "SELECT full_name, email, photo FROM employee";
-$result = @mysqli_query($query);
+$result = @mysqli_query($mm, $query);
 
-while ($row = mysqli_fetch_assoc($result))
+while ($row = mysqli_fetch_assoc($mm, $result))
 {
     // HTML body
     $body  = "Hello &lt;font size=\"4\"&gt;" . $row['full_name'] . "&lt;/font&gt;, &lt;p&gt;";
@@ -126,4 +125,4 @@ if(!$mail->send())
 echo 'Message was sent successfully';
 </pre>
 </body>
-</html>
+</html>
\ No newline at end of file