diff --git a/.idea/misc.xml b/.idea/misc.xml
index 58918f5..031fcf3 100644
--- a/.idea/misc.xml
+++ b/.idea/misc.xml
@@ -1,4 +1,10 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
+  <component name="JavadocGenerationManager">
+    <option name="OUTPUT_DIRECTORY" value="$USER_HOME$/Desktop/ClassroomInteraction_javadoc" />
+    <option name="OPTION_DOCUMENT_TAG_AUTHOR" value="true" />
+    <option name="OPTION_DOCUMENT_TAG_VERSION" value="true" />
+    <option name="OTHER_OPTIONS" value="-encoding utf-8 -charset utf-8" />
+  </component>
   <component name="ProjectRootManager" version="2" languageLevel="JDK_1_8" default="true" project-jdk-name="1.8" project-jdk-type="JavaSDK" />
 </project>
\ No newline at end of file
diff --git a/Library/src/main/java/com/cfive/classroom/library/database/DatabaseHelper.java b/Library/src/main/java/com/cfive/classroom/library/database/DatabaseHelper.java
index 55ccc9b..15fa7b8 100644
--- a/Library/src/main/java/com/cfive/classroom/library/database/DatabaseHelper.java
+++ b/Library/src/main/java/com/cfive/classroom/library/database/DatabaseHelper.java
@@ -10,273 +10,766 @@ import com.sun.istack.internal.Nullable;
 
 import java.security.NoSuchAlgorithmException;
 import java.security.spec.InvalidKeySpecException;
-import java.sql.Connection;
-import java.sql.PreparedStatement;
-import java.sql.ResultSet;
-import java.sql.SQLException;
+import java.sql.*;
 import java.time.LocalDateTime;
+import java.time.ZoneOffset;
 import java.util.ArrayList;
 import java.util.List;
 
+/**
+ * 数据库操作集合类
+ * 所有数据库操作方法全部在这里
+ *
+ * @author FatttSnake
+ * @version 2.1
+ */
 public class DatabaseHelper {
+    /**
+     * 查询所有院系
+     *
+     * @return <code>List</code> 包含 Faculty 类型的数组
+     * @see List
+     */
     public static List<Faculty> selectAllFromFaculty() throws NoConfigException, SQLException {
         return FacultyOA.selectAll();
     }
 
+    /**
+     * 通过院系编号查询院系
+     *
+     * @param facID 院系编号
+     * @return <code>Faculty</code> 院系类
+     * @see Faculty
+     */
     public static Faculty selectFromFaculty(int facID) throws NoConfigException, SQLException {
         return FacultyOA.select(facID);
     }
 
+    /**
+     * 通过院系名查询院系
+     *
+     * @param facName 院系名
+     * @return <code>Faculty</code> 院系类
+     * @see Faculty
+     */
     public static Faculty selectFromFaculty(String facName) throws NoConfigException, SQLException {
         return FacultyOA.select(facName);
     }
 
+    /**
+     * 插入院系
+     *
+     * @param facName 院系名
+     * @return <code>Faculty</code> 院系类
+     * @see Faculty
+     */
     public static Faculty insertIntoFaculty(String facName) throws NoConfigException, SQLException, InsertException, AlreadyExistsException {
         return FacultyOA.insert(facName);
     }
 
+    /**
+     * 插入院系（指定院系编号）
+     *
+     * @param facID 院系编号
+     * @param facName 院系名
+     * @return <code>Faculty</code> 院系类
+     * @see Faculty
+     */
     public static Faculty insertIntoFaculty(int facID, String facName) throws NoConfigException, InsertException, SQLException, AlreadyExistsException {
         return FacultyOA.insert(facID, facName);
     }
 
+    /**
+     * 通过院系编号查询院系是否存在
+     *
+     * @param facID 院系编号
+     * @return <code>true</code> 存在
+     * <code>false</code> 不存在
+     */
     public static boolean isExistsInFaculty(int facID) throws NoConfigException, SQLException {
         return FacultyOA.isExists(facID);
     }
 
+    /**
+     * 通过院系名查询院系是否存在
+     *
+     * @param facName 院系名
+     * @return <code>true</code> 存在
+     * <code>false</code> 不存在
+     */
     public static boolean isExistsInFaculty(String facName) throws NoConfigException, SQLException {
         return FacultyOA.isExists(facName);
     }
 
+    /**
+     * 通过院系编号删除院系
+     *
+     * @param facID 院系编号
+     * @return <code>true</code> 成功
+     * <code>false</code> 失败
+     */
     public static boolean deleteFromFaculty(int facID) throws NoConfigException, SQLException {
         return FacultyOA.delete(facID);
     }
 
+    /**
+     * 通过院系名删除院系
+     *
+     * @param facName 院系名
+     * @return <code>true</code> 成功
+     * <code>false</code> 失败
+     */
     public static boolean deleteFromFaculty(String facName) throws NoConfigException, SQLException {
         return FacultyOA.delete(facName);
     }
 
+    /**
+     * 查询所有科目
+     *
+     * @return <code>List</code> 包含 Subject 类型的数组
+     * @see List
+     */
     public static List<Subject> selectAllFromSubject() throws NoConfigException, SQLException {
         return SubjectOA.selectAll();
     }
 
+    /**
+     * 通过科目编号查询科目
+     *
+     * @param subID 科目编号
+     * @return <code>Subject</code> 科目类
+     * @see Subject
+     */
     public static Subject selectFromSubject(int subID) throws NoConfigException, SQLException {
         return SubjectOA.select(subID);
     }
 
+    /**
+     * 通过科目名查询科目
+     *
+     * @param subName 科目名
+     * @return <code>Subject</code> 科目类
+     * @see Subject
+     */
     public static Subject selectFromSubject(String subName) throws NoConfigException, SQLException {
         return SubjectOA.select(subName);
     }
 
+    /**
+     * 插入科目
+     *
+     * @param subName 科目名
+     * @return <code>Subject</code> 科目类
+     * @see Subject
+     */
     public static Subject insertIntoSubject(String subName) throws NoConfigException, SQLException, InsertException, AlreadyExistsException {
         return SubjectOA.insert(subName);
     }
 
+    /**
+     * 插入科目（指定科目编号）
+     *
+     * @param subID 科目编号
+     * @param subName 科目名
+     * @return <code>Subject</code> 科目类
+     * @see Subject
+     */
     public static Subject insertIntoSubject(int subID, String subName) throws NoConfigException, SQLException, InsertException, AlreadyExistsException {
         return SubjectOA.insert(subID, subName);
     }
 
+    /**
+     * 通过科目编号查询科目是否存在
+     *
+     * @param subID 科目编号
+     * @return <code>true</code> 存在
+     * <code>false</code> 不存在
+     */
     public static boolean isExistsInSubject(int subID) throws NoConfigException, SQLException {
         return SubjectOA.isExists(subID);
     }
 
+    /**
+     * 通过科目名查询科目是否存在
+     *
+     * @param subName 科目名
+     * @return <code>true</code> 存在
+     * <code>false</code> 不存在
+     */
     public static boolean isExistsInSubject(String subName) throws NoConfigException, SQLException {
         return SubjectOA.isExists(subName);
     }
 
+    /**
+     * 通过科目编号删除科目
+     *
+     * @param subID 科目编号
+     * @return <code>true</code> 成功
+     * <code>false</code> 失败
+     */
     public static boolean deleteFromSubject(int subID) throws NoConfigException, SQLException {
         return SubjectOA.delete(subID);
     }
 
+    /**
+     * 通过科目名删除科目
+     *
+     * @param subName 科目名
+     * @return <code>true</code> 成功
+     * <code>false</code> 失败
+     */
     public static boolean deleteFromSubject(String subName) throws NoConfigException, SQLException {
         return SubjectOA.delete(subName);
     }
 
+    /**
+     * 查询所有专业
+     *
+     * @return <code>List</code> 包含 Major 类型的数组
+     * @see List
+     */
     public static List<Major> selectAllFromMajor() throws NoConfigException, SQLException {
         return MajorOA.selectAll();
     }
 
+    /**
+     * 通过专业编号查询专业
+     *
+     * @param majorID 专业编号
+     * @return <code>Major</code> 专业类
+     * @see Major
+     */
     public static Major selectFromMajor(int majorID) throws NoConfigException, SQLException {
         return MajorOA.select(majorID);
     }
 
+    /**
+     * 通过专业名查询专业
+     *
+     * @param majorName 专业名
+     * @return <code>Major</code> 专业类
+     * @see Major
+     */
     public static Major selectFromMajor(String majorName) throws NoConfigException, SQLException {
         return MajorOA.select(majorName);
     }
 
+    /**
+     * 插入专业
+     *
+     * @param majorName 专业名
+     * @param facID 隶属院系编号
+     * @return <code>Major</code> 专业类
+     * @see Major
+     */
     public static Major insertIntoMajor(String majorName, int facID) throws NoConfigException, SQLException, InsertException, AlreadyExistsException, DependenciesNotFoundException {
         return MajorOA.insert(majorName, facID);
     }
 
+    /**
+     * 插入专业
+     *
+     * @param majorName 专业名
+     * @param facName 隶属院系名
+     * @return <code>Major</code> 专业
+     * @see Major
+     */
     public static Major insertIntoMajor(String majorName, String facName) throws NoConfigException, AlreadyExistsException, SQLException, InsertException, DependenciesNotFoundException {
         return MajorOA.insert(majorName, facName);
     }
 
+    /**
+     * 插入专业（指定专业编号）
+     *
+     * @param majorID 专业编号
+     * @param majorName 专业名
+     * @param facID 隶属院系
+     * @return <code>Major</code> 专业类
+     * @see Major
+     */
     public static Major insertIntoMajor(int majorID, String majorName, int facID) throws NoConfigException, SQLException, InsertException, AlreadyExistsException, DependenciesNotFoundException {
         return MajorOA.insert(majorID, majorName, facID);
     }
 
+    /**
+     * 插入专业（指定专业编号）
+     *
+     * @param majorID 专业编号
+     * @param majorName 专业名
+     * @param facName 隶属院系
+     * @return <code>Major</code> 专业类
+     * @see Major
+     */
     public static Major insertIntoMajor(int majorID, String majorName, String facName) throws NoConfigException, AlreadyExistsException, SQLException, InsertException, DependenciesNotFoundException {
         return MajorOA.insert(majorID, majorName, facName);
     }
 
+    /**
+     * 通过专业编号查询专业是否存在
+     *
+     * @param majorID 专业编号
+     * @return <code>true</code> 存在
+     * <code>false</code> 不存在
+     */
     public static boolean isExistsInMajor(int majorID) throws NoConfigException, SQLException {
         return MajorOA.isExists(majorID);
     }
 
+    /**
+     * 通过专业名查询专业是否存在
+     *
+     * @param majorName 专业名
+     * @return <code>true</code> 存在
+     * <code>false</code> 不存在
+     */
     public static boolean isExistsInMajor(String majorName) throws NoConfigException, SQLException {
         return MajorOA.isExists(majorName);
     }
 
+    /**
+     * 通过专业编号删除专业
+     *
+     * @param majorID 专业编号
+     * @return <code>true</code> 成功
+     * <code>false</code> 失败
+     */
     public static boolean deleteFromMajor(int majorID) throws NoConfigException, SQLException {
         return MajorOA.delete(majorID);
     }
 
+    /**
+     * 通过专业名删除专业
+     *
+     * @param majorName 专业名
+     * @return <code>true</code> 成功
+     * <code>false</code> 失败
+     */
     public static boolean deleteFromMajor(String majorName) throws NoConfigException, SQLException {
         return MajorOA.delete(majorName);
     }
 
+    /**
+     * 查询所有班级
+     *
+     * @return <code>List</code> 包含 AClass 类型的数组
+     * @see List
+     */
     public static List<AClass> selectAllFromClass() throws NoConfigException, SQLException {
         return ClassOA.selectAll();
     }
 
+    /**
+     * 通过班级编号查询班级
+     *
+     * @param classID 班级编号
+     * @return <code>AClass</code> 班级类
+     * @see AClass
+     */
     public static AClass selectFromClass(long classID) throws NoConfigException, SQLException {
         return ClassOA.select(classID);
     }
 
+    /**
+     * 通过专业ID，年级，班号查询班级
+     *
+     * @param majorID 专业编号
+     * @param grade 年级
+     * @param classNum 班号
+     * @return <code>AClass</code> 班级类
+     * @see AClass
+     */
     public static AClass selectFromClass(int majorID, int grade, int classNum) throws NoConfigException, SQLException {
         return ClassOA.select(majorID, grade, classNum);
     }
 
+    /**
+     * 插入班级
+     *
+     * @param majorID 隶属专业
+     * @param grade 年级
+     * @param classNum 班号
+     * @return <code>AClass</code> 班级类
+     * @see AClass
+     */
     public static AClass insertIntoClass(int majorID, int grade, int classNum) throws NoConfigException, SQLException, InsertException, AlreadyExistsException, DependenciesNotFoundException {
         return ClassOA.insert(majorID, grade, classNum);
     }
 
+    /**
+     * 插入班级
+     *
+     * @param majorName 隶属专业
+     * @param grade 年级
+     * @param classNum 班号
+     * @return <code>AClass</code> 班级类
+     * @see AClass
+     */
     public static AClass insertIntoClass(String majorName, int grade, int classNum) throws NoConfigException, SQLException, InsertException, AlreadyExistsException, DependenciesNotFoundException {
         return ClassOA.insert(majorName, grade, classNum);
     }
 
+    /**
+     * 插入班级（指定班级编号）
+     *
+     * @param classID 班级编号
+     * @param majorID 隶属专业
+     * @param grade 年级
+     * @param classNum 班号
+     * @return <code>AClass</code> 班级类
+     * @see AClass
+     */
     public static AClass insertIntoClass(long classID, int majorID, int grade, int classNum) throws NoConfigException, AlreadyExistsException, SQLException, InsertException, DependenciesNotFoundException {
         return ClassOA.insert(classID, majorID, grade, classNum);
     }
 
+    /**
+     * 插入班级（指定班级编号）
+     *
+     * @param classID 班级编号
+     * @param majorName 隶属专业
+     * @param grade 年级
+     * @param classNum 班号
+     * @return <code>AClass</code> 班级类
+     * @see AClass
+     */
     public static AClass insertIntoClass(long classID, String majorName, int grade, int classNum) throws NoConfigException, AlreadyExistsException, SQLException, InsertException, DependenciesNotFoundException {
         return ClassOA.insert(classID, majorName, grade, classNum);
     }
 
+    /**
+     * 通过班级编号查询班级是否存在
+     *
+     * @param classID 班级编号
+     * @return <code>true</code> 存在
+     * <code>false</code> 不存在
+     */
     public static boolean isExistsInClass(long classID) throws NoConfigException, SQLException {
         return ClassOA.isExists(classID);
     }
 
+    /**
+     * 通过隶属专业编号，年级，班号查询班级是否存在
+     * @param majorID 专业编号
+     * @param grade 年级
+     * @param classNum 班号
+     * @return <code>true</code> 存在
+     * <code>false</code> 不存在
+     */
     public static boolean isExistsInClass(int majorID, int grade, int classNum) throws NoConfigException, SQLException {
         return ClassOA.isExists(majorID, grade, classNum);
     }
 
+    /**
+     * 通过班级编号删除班级
+     *
+     * @param classID 班级编号
+     * @return <code>true</code> 成功
+     * <code>false</code> 失败
+     */
     public static boolean deleteFromClass(long classID) throws NoConfigException, SQLException {
         return ClassOA.delete(classID);
     }
 
+    /**
+     * 通过隶属专业编号，年级，班号
+     *
+     * @param majorID 隶属专业
+     * @param grade 年级
+     * @param classNum 班号
+     * @return <code>true</code> 成功
+     * <code>false</code> 失败
+     */
     public static boolean deleteFromClass(int majorID, int grade, int classNum) throws NoConfigException, SQLException {
         return ClassOA.delete(majorID, grade, classNum);
     }
 
+    /**
+     * 查询所有学生
+     *
+     * @return <code>List</code> 包含 Student 类型的数组
+     * @see List
+     */
     public static List<Student> selectAllFromStudent() throws NoConfigException, SQLException {
         return StudentOA.selectAll();
     }
 
+    /**
+     * 通过学生编号查询学生
+     *
+     * @param stuID 学生编号
+     * @return <code>Student</code> 学生类
+     * @see Student
+     */
     public static Student selectFromStudent(long stuID) throws NoConfigException, SQLException {
         return StudentOA.select(stuID);
     }
 
+    /**
+     * 学生检验密码
+     *
+     * @param stuID 学生编号
+     * @param passwd 密码
+     * @return <code>true</code> 成功
+     * <code>false</code> 失败
+     */
     public static boolean checkPasswdInStudent(long stuID, String passwd) throws NoConfigException, SQLException, DependenciesNotFoundException, NoSuchAlgorithmException, InvalidKeySpecException {
         return StudentOA.checkPasswd(stuID, passwd);
     }
 
+    /**
+     * 学生更改密码
+     *
+     * @param stuID 学生编号
+     * @param passwd 密码
+     * @return <code>true</code> 成功
+     * <code>false</code> 失败
+     */
     public static boolean changePasswdInStudent(long stuID, String passwd) throws NoConfigException, SQLException, DependenciesNotFoundException, NoSuchAlgorithmException, InvalidKeySpecException {
         return StudentOA.changePasswd(stuID, passwd);
     }
 
+    /**
+     * 插入学生
+     *
+     * @param stuID 学号
+     * @param stuName 学生姓名
+     * @param gender 性别
+     * @param classID 隶属班级
+     * @param passwd 密码
+     * @return <code>Student</code> 学生类
+     * @see Student
+     */
     public static Student insertIntoStudent(long stuID, String stuName, Gender gender, long classID, String passwd) throws NoConfigException, SQLException, InsertException, AlreadyExistsException, DependenciesNotFoundException, NoSuchAlgorithmException, InvalidKeySpecException {
         return StudentOA.insert(stuID, stuName, gender, classID, passwd);
     }
 
+    /**
+     * 通过学生编号查询学生是否存在
+     *
+     * @param stuID 学生编号
+     * @return <code>true</code> 存在
+     * <code>false</code> 不存在
+     */
     public static boolean isExistsInStudent(long stuID) throws NoConfigException, SQLException {
         return StudentOA.isExists(stuID);
     }
 
+    /**
+     * 通过学生编号删除学生
+     *
+     * @param stuID 学生编号
+     * @return <code>true</code> 成功
+     * <code>false</code> 失败
+     */
     public static boolean deleteFromStudent(long stuID) throws NoConfigException, SQLException {
         return StudentOA.delete(stuID);
     }
 
+    /**
+     * 查询所有教师
+     *
+     * @return <code>List</code> 包含 Teacher 类型的数组
+     * @see List
+     */
     public static List<Teacher> selectAllFromTeacher() throws NoConfigException, SQLException {
         return TeacherOA.selectAll();
     }
 
+    /**
+     * 通过教师编号查询教师
+     *
+     * @param tchID 教师编号
+     * @return <code>Teacher</code> 教师类
+     * @see Teacher
+     */
     public static Teacher selectFromTeacher(int tchID) throws NoConfigException, SQLException {
         return TeacherOA.select(tchID);
     }
 
+    /**
+     * 教师检验密码
+     *
+     * @param tchID 教师编号
+     * @param passwd 密码
+     * @return <code>true</code> 成功
+     * <code>false</code> 失败
+     */
     public static boolean checkPasswdInTeacher(long tchID, String passwd) throws NoConfigException, SQLException, DependenciesNotFoundException, NoSuchAlgorithmException, InvalidKeySpecException {
         return TeacherOA.checkPasswd(tchID, passwd);
     }
 
+    /**
+     * 教师更改密码
+     *
+     * @param tchID 教师编号
+     * @param passwd 密码
+     * @return <code>true</code> 成功
+     * <code>false</code> 失败
+     */
     public static boolean changePasswdInTeacher(long tchID, String passwd) throws NoConfigException, SQLException, DependenciesNotFoundException, NoSuchAlgorithmException, InvalidKeySpecException {
         return TeacherOA.changePasswd(tchID, passwd);
     }
 
+    /**
+     * 插入教师
+     *
+     * @param tchID 教师编号
+     * @param tchName 教师姓名
+     * @param gender 性别
+     * @param facID 隶属院系
+     * @param passwd 密码
+     * @return <code>Teacher</code> 教师类
+     * @see Teacher
+     */
     public static Teacher insertIntoTeacher(long tchID, String tchName, Gender gender, int facID, String passwd) throws NoConfigException, SQLException, InsertException, AlreadyExistsException, DependenciesNotFoundException, NoSuchAlgorithmException, InvalidKeySpecException {
         return TeacherOA.insert(tchID, tchName, gender, facID, passwd);
     }
 
+    /**
+     * 通过教师编号查询教师是否存在
+     *
+     * @param tchID 教师编号
+     * @return <code>true</code> 存在
+     * <code>false</code> 不存在
+     */
     public static boolean isExistsInTeacher(long tchID) throws NoConfigException, SQLException {
         return TeacherOA.isExists(tchID);
     }
 
+    /**
+     * 通过教师编号删除教师
+     *
+     * @param tchID 教师编号
+     * @return <code>true</code> 成功
+     * <code>false</code> 失败
+     */
     public static boolean deleteFromTeacher(long tchID) throws NoConfigException, SQLException {
         return TeacherOA.delete(tchID);
     }
 
+    /**
+     * 查询所有课程
+     *
+     * @return <code>List</code> 包含 Course 类型的数组
+     * @see List
+     */
     public static List<Course> selectAllFromCourse() throws NoConfigException, SQLException {
         return CourseOA.selectAll();
     }
 
+    /**
+     * 通过课程编号查询课程
+     *
+     * @param courID 课程编号
+     * @return <code>Course</code> 课程类
+     * @see Course
+     */
     public static Course selectFromCourse(long courID) throws NoConfigException, SQLException {
         return CourseOA.select(courID);
     }
 
+    /**
+     * 插入课程
+     *
+     * @param courID 课程编号
+     * @param subID 隶属专业
+     * @param tchID 隶属教师
+     * @param courTimeStart 课程开始时间
+     * @param courTimeEnd 课程结束时间
+     * @return <code>Course</code> 课程类
+     * @see Course
+     */
     public static Course insertIntoCourse(long courID, int subID, long tchID, LocalDateTime courTimeStart, LocalDateTime courTimeEnd) throws NoConfigException, SQLException, InsertException, AlreadyExistsException, DependenciesNotFoundException {
         return CourseOA.insert(courID, subID, tchID, courTimeStart, courTimeEnd);
     }
 
+    /**
+     * 通过课程编号查询课程是否存在
+     *
+     * @param courID 课程编号
+     * @return <code>true</code> 存在
+     * <code>false</code> 不存在
+     */
     public static boolean isExistsInCourse(long courID) throws NoConfigException, SQLException {
         return CourseOA.isExists(courID);
     }
 
+    /**
+     * 通过课程编号删除课程
+     *
+     * @param courID 课程编号
+     * @return <code>true</code> 成功
+     * <code>false</code> 失败
+     */
     public static boolean deleteFromCourse(long courID) throws NoConfigException, SQLException {
         return CourseOA.delete(courID);
     }
 
+    /**
+     * 查询所有考勤
+     *
+     * @return <code>List</code> 包含 Attendance 类型的数组
+     * @see List
+     */
     public static List<Attendance> selectAllFromAttendance() throws NoConfigException, SQLException {
         return AttendanceOA.selectAll();
     }
 
+    /**
+     * 通过考勤编号查询考勤
+     *
+     * @param attID 考勤编号
+     * @return <code>Attendance</code> 考勤类
+     * @see Attendance
+     */
     public static Attendance selectFromAttendance(String attID) throws NoConfigException, SQLException {
         return AttendanceOA.select(attID);
     }
 
+    /**
+     * 插入考勤
+     *
+     * @param courID 隶属课程
+     * @param stuID 隶属学生
+     * @param attTime 考勤时间
+     * @param attStatus 考勤状态
+     * @return <code>Attendance</code> 考勤类
+     * @see Attendance
+     */
     public static Attendance insertIntoAttendance(long courID, long stuID, @Nullable LocalDateTime attTime, AttStatus attStatus) throws NoConfigException, SQLException, InsertException, AlreadyExistsException, DependenciesNotFoundException {
         return AttendanceOA.insert(courID, stuID, attTime, attStatus);
     }
 
+    /**
+     * 通过考勤编号查询考勤是否存在
+     * @param attID 考勤编号
+     * @return <code>true</code> 存在
+     * <code>false</code> 不存在
+     */
     public static boolean isExistsInAttendance(String attID) throws NoConfigException, SQLException {
         return AttendanceOA.isExists(attID);
     }
 
+    /**
+     * 通过考勤编号删除考勤
+     *
+     * @param attID 考勤编号
+     * @return <code>true</code> 成功
+     * <code>false</code> 失败
+     */
     public static boolean deleteFromAttendance(String attID) throws NoConfigException, SQLException {
         return AttendanceOA.delete(attID);
     }
 
+    /**
+     * 查询教师所授课程
+     *
+     * @param tchID 教师编号
+     * @return <code>List</code> 包含 Course 类型的数组
+     * @see List
+     */
     public static List<Course> queryCourses(long tchID) throws NoConfigException, SQLException, DependenciesNotFoundException {
-        if (!isExistsInTeacher(tchID)) throw new DependenciesNotFoundException();
+        if (!TeacherOA.isExists(tchID)) throw new DependenciesNotFoundException();
         ArrayList<Course> courses = new ArrayList<>();
         String sql = "SELECT courID FROM course,teacher WHERE course.tchID=teacher.tchID AND course.tchID=?";
         try (Connection connection = PoolHelper.getConnection()) {
@@ -284,7 +777,7 @@ public class DatabaseHelper {
                 preparedStatement.setLong(1, tchID);
                 try (ResultSet resultSet = preparedStatement.executeQuery()) {
                     while (resultSet.next()) {
-                        courses.add(selectFromCourse(resultSet.getLong("courID")));
+                        courses.add(CourseOA.select(resultSet.getLong("courID")));
                     }
                 }
             }
@@ -292,8 +785,15 @@ public class DatabaseHelper {
         return courses;
     }
 
+    /**
+     * 查询课程所有学生
+     *
+     * @param courID 课程编号
+     * @return <code>List</code> 包含 Student 类型的数组
+     * @see List
+     */
     public static List<Student> selectStudentsFromCourse(long courID) throws DependenciesNotFoundException, NoConfigException, SQLException {
-        if (!isExistsInCourse(courID)) throw new DependenciesNotFoundException();
+        if (!CourseOA.isExists(courID)) throw new DependenciesNotFoundException();
 
         ArrayList<Student> students = new ArrayList<>();
         String sql = "SELECT stuID FROM attendance WHERE courID=?";
@@ -310,21 +810,41 @@ public class DatabaseHelper {
         return students;
     }
 
-    public static boolean updateAttendance(String attID, AttStatus attStatus) throws NoConfigException, SQLException, DependenciesNotFoundException {
-        if (!isExistsInAttendance(attID)) throw new DependenciesNotFoundException();
+    /**
+     * 更新考勤状态
+     *
+     * @param attID 考勤编号
+     * @param attStatus 考勤状态
+     * @param attTime 考勤时间（可空）
+     * @return <code>true</code> 成功
+     * <code>false</code> 失败
+     */
+    public static boolean updateAttendance(String attID, AttStatus attStatus, @Nullable LocalDateTime attTime) throws NoConfigException, SQLException, DependenciesNotFoundException {
+        if (!AttendanceOA.isExists(attID)) throw new DependenciesNotFoundException();
 
-        String sql = "UPDATE attendance SET attStatus=? WHERE attID=?";
+        String sql = "UPDATE attendance SET attStatus=?,attTime=? WHERE attID=?";
         try (Connection connection = PoolHelper.getConnection()) {
             try (PreparedStatement preparedStatement = connection.prepareStatement(sql)) {
                 preparedStatement.setString(1, attStatus.name());
-                preparedStatement.setString(2, attID);
+                if (attTime == null) {
+                    preparedStatement.setTimestamp(2, null);
+                } else {
+                    preparedStatement.setTimestamp(2, new Timestamp(attTime.toEpochSecond(ZoneOffset.of("+8")) * 1000));
+                }
+                preparedStatement.setString(3, attID);
                 return preparedStatement.executeUpdate() == 1;
             }
         }
     }
 
+    /**
+     * 查询课程考勤
+     * @param courID 课程编号
+     * @return <code>List</code> 包含 Attendance 类型的数组
+     * @see List
+     */
     public static List<Attendance> selectAttendanceByCourse(long courID) throws NoConfigException, SQLException, DependenciesNotFoundException {
-        if (!isExistsInCourse(courID)) throw new DependenciesNotFoundException();
+        if (!CourseOA.isExists(courID)) throw new DependenciesNotFoundException();
 
         ArrayList<Attendance> attendances = new ArrayList<>();
         String sql = "SELECT attID FROM attendance WHERE courID=?";
@@ -341,6 +861,9 @@ public class DatabaseHelper {
         return attendances;
     }
 
+    /**
+     * 关闭数据库
+     */
     public static void close() {
         PoolHelper.close();
     }
diff --git a/Library/src/main/java/com/cfive/classroom/library/database/util/AlreadyExistsException.java b/Library/src/main/java/com/cfive/classroom/library/database/util/AlreadyExistsException.java
index 8b37f69..3360f35 100644
--- a/Library/src/main/java/com/cfive/classroom/library/database/util/AlreadyExistsException.java
+++ b/Library/src/main/java/com/cfive/classroom/library/database/util/AlreadyExistsException.java
@@ -1,5 +1,11 @@
 package com.cfive.classroom.library.database.util;
 
+/**
+ * 项目已存在异常
+ *
+ * @author FatttSnake
+ * @version 1.0
+ */
 public class AlreadyExistsException extends Exception {
     public AlreadyExistsException() {
         super("This item already exists");
diff --git a/Library/src/main/java/com/cfive/classroom/library/database/util/DependenciesNotFoundException.java b/Library/src/main/java/com/cfive/classroom/library/database/util/DependenciesNotFoundException.java
index 70ab93c..3787823 100644
--- a/Library/src/main/java/com/cfive/classroom/library/database/util/DependenciesNotFoundException.java
+++ b/Library/src/main/java/com/cfive/classroom/library/database/util/DependenciesNotFoundException.java
@@ -1,5 +1,11 @@
 package com.cfive.classroom.library.database.util;
 
+/**
+ * 依赖项不存在异常
+ *
+ * @author FatttSnake
+ * @version 1.0
+ */
 public class DependenciesNotFoundException extends Exception {
     public DependenciesNotFoundException() {
         super("Could not found dependencies");
diff --git a/Library/src/main/java/com/cfive/classroom/library/database/util/InsertException.java b/Library/src/main/java/com/cfive/classroom/library/database/util/InsertException.java
index f1e247a..0d4986f 100644
--- a/Library/src/main/java/com/cfive/classroom/library/database/util/InsertException.java
+++ b/Library/src/main/java/com/cfive/classroom/library/database/util/InsertException.java
@@ -1,5 +1,11 @@
 package com.cfive.classroom.library.database.util;
 
+/**
+ * 插入异常
+ *
+ * @author FatttSnake
+ * @version 1.0
+ */
 public class InsertException extends Exception {
     public InsertException() {
         super("Could not insert the data into database");
diff --git a/Library/src/main/java/com/cfive/classroom/library/database/util/NoConfigException.java b/Library/src/main/java/com/cfive/classroom/library/database/util/NoConfigException.java
index 262520f..fb7670b 100644
--- a/Library/src/main/java/com/cfive/classroom/library/database/util/NoConfigException.java
+++ b/Library/src/main/java/com/cfive/classroom/library/database/util/NoConfigException.java
@@ -1,5 +1,11 @@
 package com.cfive.classroom.library.database.util;
 
+/**
+ * 无配置文件异常
+ *
+ * @author FatttSnake
+ * @version 1.0
+ */
 public class NoConfigException extends Exception {
     public NoConfigException() {
         super("Could not load configuration file");
diff --git a/Library/src/main/java/com/cfive/classroom/library/database/util/PBKDF2Util.java b/Library/src/main/java/com/cfive/classroom/library/database/util/PBKDF2Util.java
index 3fcb522..243f56d 100644
--- a/Library/src/main/java/com/cfive/classroom/library/database/util/PBKDF2Util.java
+++ b/Library/src/main/java/com/cfive/classroom/library/database/util/PBKDF2Util.java
@@ -8,6 +8,12 @@ import java.security.SecureRandom;
 import java.security.spec.InvalidKeySpecException;
 import java.security.spec.KeySpec;
 
+/**
+ * PBKDF2 密码加密工具类
+ *
+ * @author FatttSnake
+ * @version 1.0
+ */
 public class PBKDF2Util {
     public static final String PBKDF2_ALGORITHM = "PBKDF2WithHmacSHA1";