diff --git a/README.md b/README.md
index a9fd61d1..d1155100 100644
--- a/README.md
+++ b/README.md
@@ -83,9 +83,7 @@
 
 更多精彩内容将发布在微信公众号 CyC2018 上，你也可以在公众号后台和我交流学习和求职相关的问题。另外，公众号提供了该项目的 PDF 等离线阅读版本，后台回复 "下载" 即可领取。公众号也提供了一份技术面试复习大纲，不仅系统整理了面试知识点，而且标注了各个知识点的重要程度，从而帮你理清多而杂的面试知识点，后台回复 "大纲" 即可领取。我基本是按照这个大纲来进行复习的，对我拿到了 BAT 头条等 Offer 起到很大的帮助。你们完全可以和我一样根据大纲上列的知识点来进行复习，就不用看很多不重要的内容，也可以知道哪些内容很重要从而多安排一些复习时间。
 
-<br>
-
-<div align="center"><img width="500px" src="https://cs-notes-1256109796.cos.ap-guangzhou.myqcloud.com/other/公众号海报3.png"></img></div>
+<div align="center"><img width="500px" src="https://cs-notes-1256109796.cos.ap-guangzhou.myqcloud.com/other/公众号海报4.png"></img></div>
 
 ### 更多内容
 
diff --git a/assets/Test.cpp b/assets/Test.cpp
deleted file mode 100644
index 31a3ad8d..00000000
--- a/assets/Test.cpp
+++ /dev/null
@@ -1,8 +0,0 @@
-#include <iostream>
-
-using namespace std;
-
-int main() {
-	cout << "CyC OvO" << endl;
-}
- 
diff --git a/assets/Test.java b/assets/Test.java
deleted file mode 100644
index fec1bb44..00000000
--- a/assets/Test.java
+++ /dev/null
@@ -1,5 +0,0 @@
-public class Test {
-    public static void main(String args[]) {
-        System.out.println("CyC OvO");
-    }
-}
diff --git a/assets/Test.py b/assets/Test.py
deleted file mode 100644
index 7042300f..00000000
--- a/assets/Test.py
+++ /dev/null
@@ -1 +0,0 @@
-print ("CyC OvO");
diff --git a/assets/download.md b/assets/download.md
index 8f71a74e..876e0b10 100644
--- a/assets/download.md
+++ b/assets/download.md
@@ -30,5 +30,5 @@
 
 离线版本由公众号 **CyC2018** 发布，最新版本也会在上面及时发布，在公众号后台回复 **离线下载** 即可获取下载链接。
 
-<div align="center"><img width="460px" src="https://cs-notes-1256109796.cos.ap-guangzhou.myqcloud.com/other/公众号海报3.png"></img></div>
+<div align="center"><img width="460px" src="https://cs-notes-1256109796.cos.ap-guangzhou.myqcloud.com/other/公众号海报4.png"></img></div>
 
diff --git a/other/sql 经典练习题.sql b/other/sql 经典练习题.sql
deleted file mode 100644
index da1ac09b..00000000
--- a/other/sql 经典练习题.sql	
+++ /dev/null
@@ -1,483 +0,0 @@
-use fuxi;
-
-CREATE TABLE STUDENT
-(
-  SNO       VARCHAR(3) NOT NULL,
-  SNAME     VARCHAR(4) NOT NULL,
-  SSEX      VARCHAR(2) NOT NULL,
-  SBIRTHDAY DATETIME,
-  CLASS     VARCHAR(5)
-);
-
-CREATE TABLE COURSE
-(
-  CNO   VARCHAR(5)  NOT NULL,
-  CNAME VARCHAR(10) NOT NULL,
-  TNO   VARCHAR(10) NOT NULL
-);
-
-CREATE TABLE SCORE
-(
-  SNO    VARCHAR(3)     NOT NULL,
-  CNO    VARCHAR(5)     NOT NULL,
-  DEGREE NUMERIC(10, 1) NOT NULL
-);
-
-CREATE TABLE TEACHER
-(
-  TNO       VARCHAR(3)  NOT NULL,
-  TNAME     VARCHAR(4)  NOT NULL,
-  TSEX      VARCHAR(2)  NOT NULL,
-  TBIRTHDAY DATETIME    NOT NULL,
-  PROF      VARCHAR(6),
-  DEPART    VARCHAR(10) NOT NULL
-);
-
-INSERT INTO STUDENT (SNO, SNAME, SSEX, SBIRTHDAY, CLASS) VALUES (108, '曾华'
-  , '男', '1977-09-01', 95033);
-INSERT INTO STUDENT (SNO, SNAME, SSEX, SBIRTHDAY, CLASS) VALUES (105, '匡明'
-  , '男', '1975-10-02', 95031);
-INSERT INTO STUDENT (SNO, SNAME, SSEX, SBIRTHDAY, CLASS) VALUES (107, '王丽'
-  , '女', '1976-01-23', 95033);
-INSERT INTO STUDENT (SNO, SNAME, SSEX, SBIRTHDAY, CLASS) VALUES (101, '李军'
-  , '男', '1976-02-20', 95033);
-INSERT INTO STUDENT (SNO, SNAME, SSEX, SBIRTHDAY, CLASS) VALUES (109, '王芳'
-  , '女', '1975-02-10', 95031);
-INSERT INTO STUDENT (SNO, SNAME, SSEX, SBIRTHDAY, CLASS) VALUES (103, '陆君'
-  , '男', '1974-06-03', 95031);
-
-INSERT INTO COURSE (CNO, CNAME, TNO) VALUES ('3-105', '计算机导论', 825);
-INSERT INTO COURSE (CNO, CNAME, TNO) VALUES ('3-245', '操作系统', 804);
-INSERT INTO COURSE (CNO, CNAME, TNO) VALUES ('6-166', '数据电路', 856);
-INSERT INTO COURSE (CNO, CNAME, TNO) VALUES ('9-888', '高等数学', 100);
-
-INSERT INTO SCORE (SNO, CNO, DEGREE) VALUES (103, '3-245', 86);
-INSERT INTO SCORE (SNO, CNO, DEGREE) VALUES (105, '3-245', 75);
-INSERT INTO SCORE (SNO, CNO, DEGREE) VALUES (109, '3-245', 68);
-INSERT INTO SCORE (SNO, CNO, DEGREE) VALUES (103, '3-105', 92);
-INSERT INTO SCORE (SNO, CNO, DEGREE) VALUES (105, '3-105', 88);
-INSERT INTO SCORE (SNO, CNO, DEGREE) VALUES (109, '3-105', 76);
-INSERT INTO SCORE (SNO, CNO, DEGREE) VALUES (101, '3-105', 64);
-INSERT INTO SCORE (SNO, CNO, DEGREE) VALUES (107, '3-105', 91);
-INSERT INTO SCORE (SNO, CNO, DEGREE) VALUES (101, '6-166', 85);
-INSERT INTO SCORE (SNO, CNO, DEGREE) VALUES (107, '6-106', 79);
-INSERT INTO SCORE (SNO, CNO, DEGREE) VALUES (108, '3-105', 78);
-INSERT INTO SCORE (SNO, CNO, DEGREE) VALUES (108, '6-166', 81);
-
-INSERT INTO TEACHER (TNO, TNAME, TSEX, TBIRTHDAY, PROF, DEPART)
-VALUES (804, '李诚', '男', '1958-12-02', '副教授', '计算机系');
-INSERT INTO TEACHER (TNO, TNAME, TSEX, TBIRTHDAY, PROF, DEPART)
-VALUES (856, '张旭', '男', '1969-03-12', '讲师', '电子工程系');
-INSERT INTO TEACHER (TNO, TNAME, TSEX, TBIRTHDAY, PROF, DEPART)
-VALUES (825, '王萍', '女', '1972-05-05', '助教', '计算机系');
-INSERT INTO TEACHER (TNO, TNAME, TSEX, TBIRTHDAY, PROF, DEPART)
-VALUES (831, '刘冰', '女', '1977-08-14', '助教', '电子工程系');
-
--- 1、 查询Student表中的所有记录的Sname、Ssex和Class列。
-select
-  SNAME,
-  SSEX,
-  CLASS
-from STUDENT;
-
--- 2、 查询教师所有的单位即不重复的Depart列。
-select distinct DEPART
-from TEACHER1;
-
--- 3、 查询Student表的所有记录。
-select *
-from STUDENT;
-
--- 4、 查询Score表中成绩在60到80之间的所有记录。
-select *
-from SCORE
-where DEGREE > 60 and DEGREE < 80;
-
--- 5、 查询Score表中成绩为85，86或88的记录。
-select *
-from SCORE
-where DEGREE = 85 or DEGREE = 86 or DEGREE = 88;
-
--- 6、 查询Student表中“95031”班或性别为“女”的同学记录。
-select *
-from STUDENT
-where CLASS = '95031' or SSEX = '女';
-
--- 7、 以Class降序查询Student表的所有记录。
-select *
-from STUDENT
-order by CLASS desc;
-
--- 8、 以Cno升序、Degree降序查询Score表的所有记录。
-select *
-from SCORE
-order by CNO asc, DEGREE desc;
-
--- 9、 查询“95031”班的学生人数。
-select count(*)
-from STUDENT
-where CLASS = '95031';
-
--- 10、查询Score表中的最高分的学生学号和课程号。
-select
-  sno,
-  CNO
-from SCORE
-where DEGREE = (
-  select max(DEGREE)
-  from SCORE
-);
-
--- 11、查询‘3-105’号课程的平均分。
-select avg(DEGREE)
-from SCORE
-where CNO = '3-105';
-
--- 12、查询Score表中至少有5名学生选修的并以3开头的课程的平均分数。
-select
-  avg(DEGREE),
-  CNO
-from SCORE
-where cno like '3%'
-group by CNO
-having count(*) > 5;
-
--- 13、查询最低分大于70，最高分小于90的Sno列。
-select SNO
-from SCORE
-group by SNO
-having min(DEGREE) > 70 and max(DEGREE) < 90;
-
--- 14、查询所有学生的Sname、Cno和Degree列。
-select
-  SNAME,
-  CNO,
-  DEGREE
-from STUDENT, SCORE
-where STUDENT.SNO = SCORE.SNO;
-
--- 15、查询所有学生的Sno、Cname和Degree列。
-select
-  SCORE.SNO,
-  CNO,
-  DEGREE
-from STUDENT, SCORE
-where STUDENT.SNO = SCORE.SNO;
-
--- 16、查询所有学生的Sname、Cname和Degree列。
-SELECT
-  A.SNAME,
-  B.CNAME,
-  C.DEGREE
-FROM STUDENT A
-  JOIN (COURSE B, SCORE C)
-    ON A.SNO = C.SNO AND B.CNO = C.CNO;
-
--- 17、查询“95033”班所选课程的平均分。
-select avg(DEGREE)
-from SCORE
-where sno in (select SNO
-              from STUDENT
-              where CLASS = '95033');
-
--- 18、假设使用如下命令建立了一个grade表：
-create table grade (
-  low  numeric(3, 0),
-  upp  numeric(3),
-  rank char(1)
-);
-insert into grade values (90, 100, 'A');
-insert into grade values (80, 89, 'B');
-insert into grade values (70, 79, 'C');
-insert into grade values (60, 69, 'D');
-insert into grade values (0, 59, 'E');
--- 现查询所有同学的Sno、Cno和rank列。
-SELECT
-  A.SNO,
-  A.CNO,
-  B.RANK
-FROM SCORE A, grade B
-WHERE A.DEGREE BETWEEN B.LOW AND B.UPP
-ORDER BY RANK;
-
--- 19、查询选修“3-105”课程的成绩高于“109”号同学成绩的所有同学的记录。
-select *
-from SCORE
-where CNO = '3-105' and DEGREE > (
-  select DEGREE
-  from SCORE
-  where SNO = '109' and CNO = '3-105'
-);
-
-set @@global.sql_mode = 'STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION';
-set sql_mode = 'STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION';
-
--- 20、查询score中选学一门以上课程的同学中分数为非最高分成绩的记录
-select *
-from SCORE
-where DEGREE < (select MAX(DEGREE)
-                from SCORE)
-group by SNO
-having count(*) > 1;
-
--- 21、查询成绩高于学号为“109”、课程号为“3-105”的成绩的所有记录。
--- 同19
-
--- 22、查询和学号为108的同学同年出生的所有学生的Sno、Sname和Sbirthday列。
-select
-  SNO,
-  SNAME,
-  SBIRTHDAY
-from STUDENT
-where year(SBIRTHDAY) = (
-  select year(SBIRTHDAY)
-  from STUDENT
-  where SNO = '108'
-);
-
--- 23、查询“张旭“教师任课的学生成绩。
-select *
-from SCORE
-where cno = (
-  select CNO
-  from COURSE
-    inner join TEACHER on COURSE.TNO = TEACHER.TNO and TNAME = '张旭'
-);
-
--- 24、查询选修某课程的同学人数多于5人的教师姓名。
-select TNAME
-from TEACHER
-where TNO = (
-  select TNO
-  from COURSE
-  where CNO = (select CNO
-               from SCORE
-               group by CNO
-               having count(SNO) > 5)
-);
-
--- 25、查询95033班和95031班全体学生的记录。
-select *
-from STUDENT
-where CLASS in ('95033', '95031');
-
--- 26、查询存在有85分以上成绩的课程Cno.
-select cno
-from SCORE
-group by CNO
-having MAX(DEGREE) > 85;
-
--- 27、查询出“计算机系“教师所教课程的成绩表。
-select *
-from SCORE
-where CNO in (select CNO
-              from TEACHER, COURSE
-              where DEPART = '计算机系' and COURSE.TNO = TEACHER.TNO);
-
--- 28、查询“计算机系”与“电子工程系“不同职称的教师的Tname和Prof
-select
-  tname,
-  prof
-from TEACHER
-where depart = '计算机系' and prof not in (
-  select prof
-  from TEACHER
-  where depart = '电子工程系'
-);
-
--- 29、查询选修编号为“3-105“课程且成绩至少高于选修编号为“3-245”的同学的Cno、Sno和Degree,并按Degree从高到低次序排序。
-select
-  CNO,
-  SNO,
-  DEGREE
-from SCORE
-where CNO = '3-105' and DEGREE > any (
-  select DEGREE
-  from SCORE
-  where CNO = '3-245'
-)
-order by DEGREE desc;
-
--- 30、查询选修编号为“3-105”且成绩高于选修编号为“3-245”课程的同学的Cno、Sno和Degree.
-SELECT *
-FROM SCORE
-WHERE DEGREE > ALL (
-  SELECT DEGREE
-  FROM SCORE
-  WHERE CNO = '3-245'
-)
-ORDER by DEGREE desc;
-
--- 31、查询所有教师和同学的name、sex和birthday.
-select
-  TNAME     name,
-  TSEX      sex,
-  TBIRTHDAY birthday
-from TEACHER
-union
-select
-  sname     name,
-  SSEX      sex,
-  SBIRTHDAY birthday
-from STUDENT;
-
--- 32、查询所有“女”教师和“女”同学的name、sex和birthday.
-select
-  TNAME     name,
-  TSEX      sex,
-  TBIRTHDAY birthday
-from TEACHER
-where TSEX = '女'
-union
-select
-  sname     name,
-  SSEX      sex,
-  SBIRTHDAY birthday
-from STUDENT
-where SSEX = '女';
-
--- 33、查询成绩比该课程平均成绩低的同学的成绩表。
-SELECT A.*
-FROM SCORE A
-WHERE DEGREE < (SELECT AVG(DEGREE)
-                FROM SCORE B
-                WHERE A.CNO = B.CNO);
-
--- 34、查询所有任课教师的Tname和Depart.
-select
-  TNAME,
-  DEPART
-from TEACHER a
-where exists(select *
-             from COURSE b
-             where a.TNO = b.TNO);
-
--- 35、查询所有未讲课的教师的Tname和Depart.
-select
-  TNAME,
-  DEPART
-from TEACHER a
-where tno not in (select tno
-                  from COURSE);
-
--- 36、查询至少有2名男生的班号。
-select CLASS
-from STUDENT
-where SSEX = '男'
-group by CLASS
-having count(SSEX) > 1;
-
--- 37、查询Student表中不姓“王”的同学记录。
-select *
-from STUDENT
-where SNAME not like "王%";
-
--- 38、查询Student表中每个学生的姓名和年龄。
-select
-  SNAME,
-  year(now()) - year(SBIRTHDAY)
-from STUDENT;
-
--- 39、查询Student表中最大和最小的Sbirthday日期值。
-select min(SBIRTHDAY) birthday
-from STUDENT
-union
-select max(SBIRTHDAY) birthday
-from STUDENT;
-
--- 40、以班号和年龄从大到小的顺序查询Student表中的全部记录。
-select *
-from STUDENT
-order by CLASS desc, year(now()) - year(SBIRTHDAY) desc;
-
--- 41、查询“男”教师及其所上的课程。
-select *
-from TEACHER, COURSE
-where TSEX = '男' and COURSE.TNO = TEACHER.TNO;
-
--- 42、查询最高分同学的Sno、Cno和Degree列。
-select
-  sno,
-  CNO,
-  DEGREE
-from SCORE
-where DEGREE = (select max(DEGREE)
-                from SCORE);
-
--- 43、查询和“李军”同性别的所有同学的Sname.
-select sname
-from STUDENT
-where SSEX = (select SSEX
-              from STUDENT
-              where SNAME = '李军');
-
--- 44、查询和“李军”同性别并同班的同学Sname.
-select sname
-from STUDENT
-where (SSEX, CLASS) = (select
-                         SSEX,
-                         CLASS
-                       from STUDENT
-                       where SNAME = '李军');
-
--- 45、查询所有选修“计算机导论”课程的“男”同学的成绩表
-select *
-from SCORE, STUDENT
-where SCORE.SNO = STUDENT.SNO and SSEX = '男' and CNO = (
-  select CNO
-  from COURSE
-  where CNAME = '计算机导论');
-
-
-
--- 46、使用游标方式来同时查询每位同学的名字，他所选课程及成绩。
-
-declare
- cursor student_cursor is
-  select S.SNO,S.SNAME,C.CNAME,SC.DEGREE as DEGREE
-  from STUDENT S, COURSE C, SCORE SC
-  where S.SNO=SC.SNO
-  and SC.CNO=C.CNO;
-
-  student_row student_cursor%ROWTYPE;
-
-begin
-  open student_cursor;
-   loop
-    fetch student_cursor INTO student_row;
-    exit when student_cursor%NOTFOUND;
-     dbms_output.put_line( student_row.SNO || '' || 
-
-student_row.SNAME|| '' || student_row.CNAME || '' ||
-
-student_row.DEGREE);
-   end loop;
-  close student_cursor;
-END;
-/ 
-
-
--- 47、 声明触发器指令，每当有同学转换班级时执行触发器显示当前和之前所在班级。
-
-CREATE OR REPLACE TRIGGER display_class_changes 
-AFTER DELETE OR INSERT OR UPDATE ON student 
-FOR EACH ROW 
-WHEN (NEW.sno > 0) 
-
-BEGIN 
-   
-   dbms_output.put_line('Old class: ' || :OLD.class); 
-   dbms_output.put_line('New class: ' || :NEW.class); 
-END; 
-/ 
-
-
-Update student
-set class=95031
-where sno=109;
-
-
--- 48、 删除已设置的触发器指令
-
-DROP TRIGGER display_class_changes;
-