本筆記來自bilibili:一天學會 MySQL 數據庫
以及參考某位大佬的筆記
 MySQL數據庫使用筆記(一):終端使用與約束
 MySQL數據庫使用筆記(二):範式設計
 MySQL數據庫使用筆記(三):查詢練習
 MySQL數據庫使用筆記(四):鏈接查詢與事務

MySQL數據庫使用筆記(三):查詢

創建數據

首先創建一個database:create database selectTest;並選擇：use selectTest;
學生表：Student（學號、姓名、性別、出生年月日、所在班級）

CREATE TABLE student(
    s_no VARCHAR(20) PRIMARY KEY COMMENT'學生學號',
    s_name VARCHAR(20) NOT NULL COMMENT'學生姓名 不能爲空',
    s_sex VARCHAR(10) NOT NULL COMMENT'學生性別',
    s_birthday DATETIME COMMENT'學生生日',
    s_class VARCHAR(20) COMMENT'學生所在的班級'
);

教師表：Teacher（教師編號、教師名字、教師性別、出生年月日、職稱、所在部門）

CREATE TABLE teacher(
    t_no VARCHAR(20) PRIMARY KEY COMMENT'教師編號',
    t_name VARCHAR(20) NOT NULL COMMENT'教師姓名',
    t_sex VARCHAR(20) NOT NULL COMMENT'教師性別',
    t_birthday DATETIME COMMENT'教師生日',
    t_rof VARCHAR(20) NOT NULL COMMENT'教師職稱',
    t_depart VARCHAR(20) NOT NULL COMMENT'教師所在的部門'
);

課程表：Course（課程號、課程名稱、教師編號）

CREATE TABLE course(
    c_no VARCHAR(20) PRIMARY KEY COMMENT'課程號',
    c_name VARCHAR(20) NOT NULL COMMENT'課程名稱',
    t_no VARCHAR(20) NOT NULL COMMENT'教師編號 外鍵關聯teacher表',
    FOREIGN KEY(t_no) references teacher(t_no)
);

成績表：Score（學號、課程號、成績）
注意:視頻中原先只有一個主鍵s_no ,後來修改了

CREATE TABLE score (
    s_no VARCHAR(20) NOT NULL COMMENT'成績表的編號 依賴學生學號',
        c_no VARCHAR(20)  NOT NULL COMMENT'課程號 依賴於課程表中的c_id',
    sc_degree decimal,
    foreign key(s_no) references student(s_no),
    foreign key(c_no) references course(c_no),
    PRIMARY KEY(s_no,c_no)
);

查看student表: desc student;

+------------+-------------+------+-----+---------+-------+
| Field      | Type        | Null | Key | Default | Extra |
+------------+-------------+------+-----+---------+-------+
| s_no       | varchar(20) | NO   | PRI | NULL    |       |
| s_name     | varchar(20) | NO   |     | NULL    |       |
| s_sex      | varchar(10) | NO   |     | NULL    |       |
| s_birthday | datetime    | YES  |     | NULL    |       |
| s_class    | varchar(20) | YES  |     | NULL    |       |
+------------+-------------+------+-----+---------+-------+

向student表中插入學生數據：

insert into student values('101', '曾華', '男', '1977-09-01', '95033');
insert into student values('102', '匡明', '男', '1975-10-02', '95031');
insert into student values('103', '王麗', '女', '1976-01-23', '95033');
insert into student values('104', '李軍', '男', '1976-02-20', '95033');
insert into student values('105', '王芳', '女', '1975-02-10', '95031');
insert into student values('106', '陸君', '男', '1974-06-03', '95031');
insert into student values('107', '王尼瑪', '男', '1976-02-20', '95033');
insert into student values('108', '張全蛋', '男', '1975-02-10', '95031');
insert into student values('109', '趙鐵柱', '男', '1974-06-03', '95031');

查看數據： select * from student;

+------+--------+-------+---------------------+---------+
| s_no | s_name | s_sex | s_birthday          | s_class |
+------+--------+-------+---------------------+---------+
| 101  | 曾華   | 男    | 1977-09-01 00:00:00 | 95033   |
| 102  | 匡明   | 男    | 1975-10-02 00:00:00 | 95031   |
| 103  | 王麗   | 女    | 1976-01-23 00:00:00 | 95033   |
| 104  | 李軍   | 男    | 1976-02-20 00:00:00 | 95033   |
| 105  | 王芳   | 女    | 1975-02-10 00:00:00 | 95031   |
| 106  | 陸君   | 男    | 1974-06-03 00:00:00 | 95031   |
| 107  | 王尼瑪 | 男    | 1976-02-20 00:00:00 | 95033   |
| 108  | 張全蛋 | 男    | 1975-02-10 00:00:00 | 95031   |
| 109  | 趙鐵柱 | 男    | 1974-06-03 00:00:00 | 95031   |
+------+--------+-------+---------------------+---------+

查看teacher表：desc teacher;

+------------+-------------+------+-----+---------+-------+
| Field      | Type        | Null | Key | Default | Extra |
+------------+-------------+------+-----+---------+-------+
| t_no       | varchar(20) | NO   | PRI | NULL    |       |
| t_name     | varchar(20) | NO   |     | NULL    |       |
| t_sex      | varchar(20) | NO   |     | NULL    |       |
| t_birthday | datetime    | YES  |     | NULL    |       |
| t_rof      | varchar(20) | NO   |     | NULL    |       |
| t_depart   | varchar(20) | NO   |     | NULL    |       |
+------------+-------------+------+-----+---------+-------+

向teacher表中插入教師信息：

INSERT INTO teacher VALUES('804','李誠','男','1958-12-02','副教授','計算機系');
INSERT INTO teacher VALUES('856','張旭','男','1969-03-12','講師','電子工程系');
INSERT INTO teacher VALUES('825','王萍','女','1972-05-05','助教','計算機系');
INSERT INTO teacher VALUES('831','劉冰','女','1977-08-14','助教','電子工程系');

查看數據：select * from teacher;

+------+--------+-------+---------------------+--------+------------+
| t_no | t_name | t_sex | t_birthday          | t_rof  | t_depart   |
+------+--------+-------+---------------------+--------+------------+
| 804  | 李誠   | 男    | 1958-12-02 00:00:00 | 副教授 | 計算機系   |
| 825  | 王萍   | 女    | 1972-05-05 00:00:00 | 助教   | 計算機系   |
| 831  | 劉冰   | 女    | 1977-08-14 00:00:00 | 助教   | 電子工程系 |
| 856  | 張旭   | 男    | 1969-03-12 00:00:00 | 講師   | 電子工程系 |
+------+--------+-------+---------------------+--------+------------+

查看course表：desc course;

+--------+-------------+------+-----+---------+-------+
| Field  | Type        | Null | Key | Default | Extra |
+--------+-------------+------+-----+---------+-------+
| c_no   | varchar(20) | NO   | PRI | NULL    |       |
| c_name | varchar(20) | NO   |     | NULL    |       |
| t_no   | varchar(20) | NO   | MUL | NULL    |       |
+--------+-------------+------+-----+---------+-------+

向course表中添加課程信息：

INSERT INTO course VALUES('3-105','計算機導論','825');
INSERT INTO course VALUES('3-245','操作系統','804');
INSERT INTO course VALUES('6-166','數字電路','856');
INSERT INTO course VALUES('9-888','高等數學','831');

查看數據: select * from course;

+-------+------------+------+
| c_no  | c_name     | t_no |
+-------+------------+------+
| 3-105 | 計算機導論 | 825  |
| 3-245 | 操作系統   | 804  |
| 6-166 | 數字電路   | 856  |
+-------+------------+------+

查看score表：desc score;

+-----------+---------------+------+-----+---------+-------+
| Field     | Type          | Null | Key | Default | Extra |
+-----------+---------------+------+-----+---------+-------+
| s_no      | varchar(20)   | NO   | PRI | NULL    |       |
| c_no      | varchar(20)   | NO   | PRI | NULL    |       |
| sc_degree | decimal(10,0) | YES  |     | NULL    |       |
+-----------+---------------+------+-----+---------+-------+

向score表中添加成績信息：

INSERT INTO score VALUES('103','3-245','86');
INSERT INTO score VALUES('105','3-245','75');
INSERT INTO score VALUES('109','3-245','68');
INSERT INTO score VALUES('103','3-105','92');
INSERT INTO score VALUES('105','3-105','88');
INSERT INTO score VALUES('109','3-105','76');
INSERT INTO score VALUES('103','6-166','85');
INSERT INTO score VALUES('105','6-166','79');
INSERT INTO score VALUES('109','6-166','81');

查看數據：select * from score;

+------+-------+-----------+
| s_no | c_no  | sc_degree |
+------+-------+-----------+
| 103  | 3-105 |        92 |
| 103  | 3-245 |        86 |
| 103  | 6-166 |        85 |
| 105  | 3-105 |        88 |
| 105  | 3-245 |        75 |
| 105  | 6-166 |        79 |
| 109  | 3-105 |        76 |
| 109  | 3-245 |        68 |
| 109  | 6-166 |        81 |
+------+-------+-----------+

查詢練習:

1、查詢s tudent表的所有記錄。

輸入：SELECT * FROM student;

+------+--------+-------+---------------------+---------+
| s_no | s_name | s_sex | s_birthday          | s_class |
+------+--------+-------+---------------------+---------+
| 101  | 曾華   | 男    | 1977-09-01 00:00:00 | 95033   |
| 102  | 匡明   | 男    | 1975-10-02 00:00:00 | 95031   |
| 103  | 王麗   | 女    | 1976-01-23 00:00:00 | 95033   |
| 104  | 李軍   | 男    | 1976-02-20 00:00:00 | 95033   |
| 105  | 王芳   | 女    | 1975-02-10 00:00:00 | 95031   |
| 106  | 陸君   | 男    | 1974-06-03 00:00:00 | 95031   |
| 107  | 王尼瑪 | 男    | 1976-02-20 00:00:00 | 95033   |
| 108  | 張全蛋 | 男    | 1975-02-10 00:00:00 | 95031   |
| 109  | 趙鐵柱 | 男    | 1974-06-03 00:00:00 | 95031   |
+------+--------+-------+---------------------+---------+

2、查詢student表中的所有記錄的sname、ssex和class列。

輸入：SELECT s_no,s_name,s_class FROM student;

+------+--------+---------+
| s_no | s_name | s_class |
+------+--------+---------+
| 101  | 曾華   | 95033   |
| 102  | 匡明   | 95031   |
| 103  | 王麗   | 95033   |
| 104  | 李軍   | 95033   |
| 105  | 王芳   | 95031   |
| 106  | 陸君   | 95031   |
| 107  | 王尼瑪 | 95033   |
| 108  | 張全蛋 | 95031   |
| 109  | 趙鐵柱 | 95031   |
+------+--------+---------+

3、查詢教師所有的單位即不重複的depart列。

輸入：SELECT distinct (t_depart) FROM teacher;
distinct表示不重複、排除重複。

+------------+
| t_depart   |
+------------+
| 計算機系   |
| 電子工程系 |
+------------+

4、查詢score表中成績在60到80之間的所有記錄。

輸入：
注意:BETWEEN… ADN… 是包含邊界的

SELECT * FROM score WHERE sc_degree BETWEEN 60 AND 80;
SELECT * FROM score WHERE sc_degree < 80 AND sc_degree > 60 ;

+------+-------+-----------+
| s_no | c_no  | sc_degree |
+------+-------+-----------+
| 105  | 3-245 |        75 |
| 105  | 6-166 |        79 |
| 109  | 3-105 |        76 |
| 109  | 3-245 |        68 |
+------+-------+-----------+

5、查詢score表中成績爲85，86或88的記錄。

這是表示一個或的關係使用in，輸入：SELECT * FROM score WHERE sc_degree IN(85, 86, 88);

+------+-------+-----------+
| s_no | c_no  | sc_degree |
+------+-------+-----------+
| 103  | 3-245 |        86 |
| 103  | 6-166 |        85 |
| 105  | 3-105 |        88 |
+------+-------+-----------+

6、查詢student表中"95031"班或性別爲“女”的同學記錄。

使用or來表示或者（不同字段），輸入：SELECT * FROM student WHERE s_class = '95031' OR s_sex = '女';

+------+--------+-------+---------------------+---------+
| s_no | s_name | s_sex | s_birthday          | s_class |
+------+--------+-------+---------------------+---------+
| 102  | 匡明   | 男    | 1975-10-02 00:00:00 | 95031   |
| 103  | 王麗   | 女    | 1976-01-23 00:00:00 | 95033   |
| 105  | 王芳   | 女    | 1975-02-10 00:00:00 | 95031   |
| 106  | 陸君   | 男    | 1974-06-03 00:00:00 | 95031   |
| 108  | 張全蛋 | 男    | 1975-02-10 00:00:00 | 95031   |
| 109  | 趙鐵柱 | 男    | 1974-06-03 00:00:00 | 95031   |
+------+--------+-------+---------------------+---------+

7、以class降序查詢student表的所有記錄。

輸入：SELECT * FROM student ORDER BY s_class desc;其中desc是降序，asc是升序。

+------+--------+-------+---------------------+---------+
| s_no | s_name | s_sex | s_birthday          | s_class |
+------+--------+-------+---------------------+---------+
| 101  | 曾華   | 男    | 1977-09-01 00:00:00 | 95033   |
| 103  | 王麗   | 女    | 1976-01-23 00:00:00 | 95033   |
| 104  | 李軍   | 男    | 1976-02-20 00:00:00 | 95033   |
| 107  | 王尼瑪 | 男    | 1976-02-20 00:00:00 | 95033   |
| 102  | 匡明   | 男    | 1975-10-02 00:00:00 | 95031   |
| 105  | 王芳   | 女    | 1975-02-10 00:00:00 | 95031   |
| 106  | 陸君   | 男    | 1974-06-03 00:00:00 | 95031   |
| 108  | 張全蛋 | 男    | 1975-02-10 00:00:00 | 95031   |
| 109  | 趙鐵柱 | 男    | 1974-06-03 00:00:00 | 95031   |
+------+--------+-------+---------------------+---------+

8、以cno升序、degree降序查詢score表的所有記錄。

先以c_no進行升序,若c_no相同,則以sc_degree降序。輸入：SELECT * FROM score ORDER BY c_no ASC,sc_degree DESC;

+------+-------+-----------+
| s_no | c_no  | sc_degree |
+------+-------+-----------+
| 103  | 3-105 |        92 |
| 105  | 3-105 |        88 |
| 109  | 3-105 |        76 |
| 103  | 3-245 |        86 |
| 105  | 3-245 |        75 |
| 109  | 3-245 |        68 |
| 103  | 6-166 |        85 |
| 109  | 6-166 |        81 |
| 105  | 6-166 |        79 |
+------+-------+-----------+

9、查詢“95031"班的學生人數。

統計使用count，輸入：SELECT COUNT(s_no) FROM student WHERE s_class = '95031';

+-------------+
| COUNT(s_no) |
+-------------+
|           5 |
+-------------+

10、查詢score表中的最高分的學生學號和課程號。 (子查詢或者排序)

輸入：select s_no,c_no from score where sc_degree= (select max(sc_degree) from score);

+------+-------+
| s_no | c_no  |
+------+-------+
| 103  | 3-105 |
+------+-------+

補充：

查詢步驟

1.先找到最高分
最高分: SELECT MAX(sc_degree) FROM score;
2.通過我們找到的最高分的分數來從score中找到我們需要的學生號和課程號

SELECT c_no, s_no FROM score WHERE sc_degree = (最高分)
SELECT c_no, s_no FROM score WHERE sc_degree = (SELECT MAX(sc_degree) FROM score);
+-------+------+
| c_no  | s_no |
+-------+------+
| 3-105 | 103  |
+-------+------+

排序步驟

排序最高分有多個的情況下可能有數據問題
limit x,y (x:表示從X條數據開始 y:需要查出多少條)
SELECT c_no, s_no FROM score ORDER BY sc_degree DESC LIMIT 0,1;這個OK
但是我們再插入一條數據:

INSERT INTO score VALUES('101','9-888','92');

再用排序法去查得到:

+-------+------+
| c_no  | s_no |
+-------+------+
| 9-888 | 101  |
+-------+------+

有兩條數據但是隻顯示一條,有問題
若我們用子查詢的方法來查詢的話會得到:

+-------+------+
| c_no  | s_no |
+-------+------+
| 9-888 | 101  |
| 3-105 | 103  |
+-------+------+

完全沒有問題.
最後爲了和視頻數據一致刪除剛剛插入的數據:

DELETE FROM score WHERE c_no = '9-888' AND s_no = '101';

11.查詢每門課的平均成績

使用avg(),比如：select avg(sc_degree) from score where c_no='3-105';
使用group by進行分組，就可以求得多組數據, 輸入：SELECT c_no,AVG(sc_degree) FROM SCORE GROUP BY c_no;

+-------+----------------+
| c_no  | AVG(sc_degree) |
+-------+----------------+
| 3-105 |        85.3333 |
| 3-245 |        76.3333 |
| 6-166 |        81.6667 |
+-------+----------------+

12.查詢score表中至少有2名學生選修的,並且以3開頭的課程的平均分

HAVING COUNT 用來計算數量，like 來模糊查詢(匹配格式)。
輸入：SELECT AVG(sc_degree),c_no from score GROUP BY c_no HAVING COUNT(c_no) >= 2 AND c_no like '3%' ;

+----------------+-------+
| AVG(sc_degree) | c_no  |
+----------------+-------+
|        85.3333 | 3-105 |
|        76.3333 | 3-245 |
+----------------+-------+

13.查詢分數大於70但是小於90的s_no列

輸入：SELECT s_no,sc_degree FROM score WHERE sc_degree BETWEEN 70 AND 90;

+------+-----------+
| s_no | sc_degree |
+------+-----------+
| 103  |        86 |
| 103  |        85 |
| 105  |        88 |
| 105  |        75 |
| 105  |        79 |
| 109  |        76 |
| 109  |        81 |
+------+-----------+

進階:顯示s_name,c_name
輸入：

select s_name,sc_degree,c_name 
FROM score,student,course 
WHERE score.s_no = student.s_no AND score.c_no = course.c_no AND sc_degree BETWEEN 70 AND 90;

+--------+-----------+------------+
| s_name | sc_degree | c_name     |
+--------+-----------+------------+
| 王麗   |        86 | 操作系統   |
| 王麗   |        85 | 數字電路   |
| 王芳   |        88 | 計算機導論 |
| 王芳   |        75 | 操作系統   |
| 王芳   |        79 | 數字電路   |
| 趙鐵柱 |        76 | 計算機導論 |
| 趙鐵柱 |        81 | 數字電路   |
+--------+-----------+------------+

14.查詢所有的學生 s_name , c_no, sc_degree列

WHERE student.s_no = score.s_no;是加入匹配條件，輸入：

SELECT s_name, c_no, sc_degree FROM student,score 
WHERE student.s_no = score.s_no;

+--------+-------+-----------+
| s_name | c_no  | sc_degree |
+--------+-------+-----------+
| 王麗   | 3-105 |        92 |
| 王麗   | 3-245 |        86 |
| 王麗   | 6-166 |        85 |
| 王芳   | 3-105 |        88 |
| 王芳   | 3-245 |        75 |
| 王芳   | 6-166 |        79 |
| 趙鐵柱 | 3-105 |        76 |
| 趙鐵柱 | 3-245 |        68 |
| 趙鐵柱 | 6-166 |        81 |
+--------+-------+-----------+

15.查詢所有學生的s_no, c_name, sc_degree列

加入條件：WHERE student.s_no = score.s_no AND score.c_no = course.c_no，輸入：SELECT student.s_no, c_name, sc_degree FROM student, course,score WHERE student.s_no = score.s_no AND score.c_no = course.c_no ;

+------+------------+-----------+
| s_no | c_name     | sc_degree |
+------+------------+-----------+
| 103  | 計算機導論 |        92 |
| 103  | 操作系統   |        86 |
| 103  | 數字電路   |        85 |
| 105  | 計算機導論 |        88 |
| 105  | 操作系統   |        75 |
| 105  | 數字電路   |        79 |
| 109  | 計算機導論 |        76 |
| 109  | 操作系統   |        68 |
| 109  | 數字電路   |        81 |
+------+------------+-----------+

16.查詢所有的學生 s_name , c_name, sc_degree列

s_name在student中，c_name在course中，sc_degree在score中。

將上面的c_no 的值換位c_name。
引入條件：WHERE student.s_no = score.s_no AND score.c_no = course.c_no，輸入：

SELECT s_name, c_name, sc_degree FROM student, course, score 
WHERE student.s_no = score.s_no AND score.c_no = course.c_no;

使用as可以重命名

+--------+------------+-----------+
| s_name | c_name     | sc_degree |
+--------+------------+-----------+
| 王麗   | 計算機導論 |        92 |
| 王麗   | 操作系統   |        86 |
| 王麗   | 數字電路   |        85 |
| 王芳   | 計算機導論 |        88 |
| 王芳   | 操作系統   |        75 |
| 王芳   | 數字電路   |        79 |
| 趙鐵柱 | 計算機導論 |        76 |
| 趙鐵柱 | 操作系統   |        68 |
| 趙鐵柱 | 數字電路   |        81 |
+--------+------------+-----------+

17.查詢班級是’95031’班學生每門課的平均分

查看95031班的數據：select * from student where s_class='95031';

+------+--------+-------+---------------------+---------+
| s_no | s_name | s_sex | s_birthday          | s_class |
+------+--------+-------+---------------------+---------+
| 102  | 匡明   | 男    | 1975-10-02 00:00:00 | 95031   |
| 105  | 王芳   | 女    | 1975-02-10 00:00:00 | 95031   |
| 106  | 陸君   | 男    | 1974-06-03 00:00:00 | 95031   |
| 108  | 張全蛋 | 男    | 1975-02-10 00:00:00 | 95031   |
| 109  | 趙鐵柱 | 男    | 1974-06-03 00:00:00 | 95031   |
+------+--------+-------+---------------------+---------+

可以通過語句：select s_no from student where s_class='95031';獲取student中的s_no。
因此可以使用in來獲取score表中的對應s_no的成績：

select * from score where s_no 
in  (select s_no  from student where s_class='95031');

+------+-------+-----------+
| s_no | c_no  | sc_degree |
+------+-------+-----------+
| 105  | 3-105 |        88 |
| 105  | 3-245 |        75 |
| 105  | 6-166 |        79 |
| 109  | 3-105 |        76 |
| 109  | 3-245 |        68 |
| 109  | 6-166 |        81 |
+------+-------+-----------+

按班級獲得平均成績：

select c_no, avg(sc_degree)
from score
where s_no in  (select s_no  from student where s_class='95031');
group by c_no;

+-------+----------------+
| c_no  | avg(sc_degree) |
+-------+----------------+
| 3-105 |        77.8333 |
+-------+----------------+

其他的查詢方式：

select c_no,AVG(sc_degree) 
from score AS sc LEFT JOIN student AS s ON sc.s_no = s.s_no 
WHERE s.s_class = '95031' 
GROUP BY sc.c_no;

SELECT sc.c_no,AVG(sc.sc_degree) 
FROM student AS s, score AS SC  
WHERE s.s_class = '95031' AND s.s_no = sc.s_no 
GROUP BY sc.c_no ;

+-------+-------------------+
| c_no  | AVG(sc.sc_degree) |
+-------+-------------------+
| 3-105 |           82.0000 |
| 3-245 |           71.5000 |
| 6-166 |           80.0000 |
+-------+-------------------+

進階**,加入課程名稱**:

SELECT sc.c_no, c.c_name, AVG(sc.sc_degree) 
FROM student AS s, score AS SC, course AS c 
WHERE s.s_class = '95031' AND s.s_no = sc.s_no AND c.c_no = sc.c_no 
GROUP BY sc.c_no ;

+-------+------------+-------------------+
| c_no  | c_name     | AVG(sc.sc_degree) |
+-------+------------+-------------------+
| 3-105 | 計算機導論 |           82.0000 |
| 3-245 | 操作系統   |           71.5000 |
| 6-166 | 數字電路   |           80.0000 |
+-------+------------+-------------------+

18.查詢選修"3-105"課程的成績高於’109’號同學’3-105’成績的所有同學的記錄

在大家都在選修3-105的背景下查詢所有分數比學號爲"109"還要高的學生信息
首先選擇’109’號同學’3-105’成績：select sc_degree from score where s_no='109' and c_no='3-105';

+-----------+
| sc_degree |
+-----------+
|        76 |
+-----------+

接着查詢成績比他高的同學：

select * from score
where sc_degree > (select sc_degree from score where s_no='109' and c_no='3-105');

+------+-------+-----------+
| s_no | c_no  | sc_degree |
+------+-------+-----------+
| 103  | 3-105 |        92 |
| 103  | 3-245 |        86 |
| 103  | 6-166 |        85 |
| 105  | 3-105 |        88 |
| 105  | 6-166 |        79 |
| 109  | 6-166 |        81 |
+------+-------+-----------+

再加上限定條件where c_no='3-105'

select * from score
where c_no='3-105' and sc_degree > (select sc_degree from score where s_no='109' and c_no='3-105');

+------+-------+-----------+
| s_no | c_no  | sc_degree |
+------+-------+-----------+
| 103  | 3-105 |        92 |
| 105  | 3-105 |        88 |
+------+-------+-----------+

19.查詢成績高於學號爲’109’,課程號爲’3-105’的成績的所有記錄

和18中的一步操作一致：

select * from score
where sc_degree > (select sc_degree from score where s_no='109' and c_no='3-105');

不過視頻中僅僅查出來了score記錄,但是並沒有學生的信息,按照上面的來修改:

SELECT * FROM student AS s, score AS sc 
WHERE sc.sc_degree > (SELECT sc_degree FROM score WHERE s_no = '109' AND c_no = '3-105') AND s.s_no = sc.s_no;

還可以再進一步:

SELECT s.s_no AS'學生學號', s.s_name AS'學生姓名', s_sex AS'性別', s_class AS'班級', c.c_no AS'課程編號', c.c_name AS'課程名稱' ,sc.sc_degree AS'分數' 
FROM student AS s, score AS sc ,course AS c 
WHERE sc.sc_degree > (SELECT sc_degree FROM score WHERE s_no = '109' AND c_no = '3-105') AND s.s_no = sc.s_no AND sc.c_no = c.c_no;

+----------+----------+------+-------+----------+------------+------+
| 學生學號 | 學生姓名 | 性別 | 班級  | 課程編號 | 課程名稱   | 分數 |
+----------+----------+------+-------+----------+------------+------+
| 103      | 王麗     | 女   | 95033 | 3-105    | 計算機導論 |   92 |
| 103      | 王麗     | 女   | 95033 | 3-245    | 操作系統   |   86 |
| 103      | 王麗     | 女   | 95033 | 6-166    | 數字電路   |   85 |
| 105      | 王芳     | 女   | 95031 | 3-105    | 計算機導論 |   88 |
| 105      | 王芳     | 女   | 95031 | 6-166    | 數字電路   |   79 |
| 109      | 趙鐵柱   | 男   | 95031 | 6-166    | 數字電路   |   81 |
+----------+----------+------+-------+----------+------------+------+

20.查詢所有學號爲108.101的同學同年出生的所有學生的s_no,s_name和s_birthday

在student表中查詢108，101的s_birthday：select year(s_birthday) from student where s_no in (108, 101);

+------------------+
| year(s_birthday) |
+------------------+
|             1977 |
|             1975 |
+------------------+

接下來輸入：

SELECT * FROM student 
WHERE YEAR(s_birthday) 
IN (SELECT YEAR(s_birthday) FROM student WHERE s_no IN('108','101'));

+------+--------+-------+---------------------+---------+
| s_no | s_name | s_sex | s_birthday          | s_class |
+------+--------+-------+---------------------+---------+
| 101  | 曾華   | 男    | 1977-09-01 00:00:00 | 95033   |
| 102  | 匡明   | 男    | 1975-10-02 00:00:00 | 95031   |
| 105  | 王芳   | 女    | 1975-02-10 00:00:00 | 95031   |
| 108  | 張全蛋 | 男    | 1975-02-10 00:00:00 | 95031   |
+------+--------+-------+---------------------+---------+

21.查詢張旭教師任課的學生的成績

首先查詢張旭的教師id：select t_no from teacher where t_name = '張旭';

+------+
| t_no |
+------+
| 856  |
+------+

獲取張旭老師教課程的id：

select c_no from course 
where t_no=(select t_no from teacher where t_name = '張旭');

+-------+
| c_no  |
+-------+
| 6-166 |
+-------+

接下來獲取這門課程所有學生的成績：

select * from score
where c_no=(select c_no from course 
where t_no=(select t_no from teacher where t_name = '張旭'));

+------+-------+-----------+
| s_no | c_no  | sc_degree |
+------+-------+-----------+
| 103  | 6-166 |        85 |
| 105  | 6-166 |        79 |
| 109  | 6-166 |        81 |
+------+-------+-----------+

22.查詢選修課程的同學人數多餘 5 人的教師姓名

爲了效果,添加數據:

INSERT INTO score VALUES('101','3-105','90');
INSERT INTO score VALUES('102','3-105','91');
INSERT INTO score VALUES('104','3-105','89');

首先查詢人數多餘5人的課程id：select c_no from score group by c_no having count(*)>5;

+-------+
| c_no  |
+-------+
| 3-105 |
+-------+

接下來查詢教這門課程的老師id：

select t_no from course 
where c_no=(select c_no from score group by c_no having count(*)>5);

+------+
| t_no |
+------+
| 825  |
+------+

再根據老師id獲取老師名字：

SELECT * FROM teacher 
WHERE t_no 
IN(SELECT t_no FROM course WHERE c_no IN (SELECT c_no FROM score GROUP BY c_no HAVING COUNT(s_no) > 5));

+------+--------+-------+---------------------+-------+----------+
| t_no | t_name | t_sex | t_birthday          | t_rof | t_depart |
+------+--------+-------+---------------------+-------+----------+
| 825  | 王萍   | 女    | 1972-05-05 00:00:00 | 助教  | 計算機系 |
+------+--------+-------+---------------------+-------+----------+

注意:視頻中用 = 是不嚴謹的,實際中你根本不知道有多少條件是符合的,要用IN

23.查詢95033班和95031班全體學生的記錄

由於視頻中就只有這兩個班,所以要插入數據:INSERT INTO student VALUES('110','張飛','男','1974-06-03','95038');
輸入：

SELECT * FROM student WHERE s_class IN('95031','95033') ORDER BY s_class ;

+------+--------+-------+---------------------+---------+
| s_no | s_name | s_sex | s_birthday          | s_class |
+------+--------+-------+---------------------+---------+
| 102  | 匡明   | 男    | 1975-10-02 00:00:00 | 95031   |
| 105  | 王芳   | 女    | 1975-02-10 00:00:00 | 95031   |
| 106  | 陸君   | 男    | 1974-06-03 00:00:00 | 95031   |
| 108  | 張全蛋 | 男    | 1975-02-10 00:00:00 | 95031   |
| 109  | 趙鐵柱 | 男    | 1974-06-03 00:00:00 | 95031   |
| 101  | 曾華   | 男    | 1977-09-01 00:00:00 | 95033   |
| 103  | 王麗   | 女    | 1976-01-23 00:00:00 | 95033   |
| 104  | 李軍   | 男    | 1976-02-20 00:00:00 | 95033   |
| 107  | 王尼瑪 | 男    | 1976-02-20 00:00:00 | 95033   |
+------+--------+-------+---------------------+---------+

進階：查詢95033班和95031班全體學生每門課的成績以及負責該課程的老師,最後以class來排序

SELECT s.s_no, s.s_name,s.s_birthday,s.s_class, c.c_no, c.c_name, sc.sc_degree , t.t_name 
FROM student AS s, course AS c, score AS sc,teacher AS t 
WHERE  s.s_class IN('95031','95033') AND s.s_no = sc.s_no AND sc.c_no = c.c_no AND c.t_no = t.t_no;

+------+--------+---------------------+---------+-------+------------+-----------+--------+
| s_no | s_name | s_birthday          | s_class | c_no  | c_name     | sc_degree | t_name |
+------+--------+---------------------+---------+-------+------------+-----------+--------+
| 101  | 曾華   | 1977-09-01 00:00:00 | 95033   | 3-105 | 計算機導論 |        90 | 王萍   |
| 102  | 匡明   | 1975-10-02 00:00:00 | 95031   | 3-105 | 計算機導論 |        91 | 王萍   |
| 103  | 王麗   | 1976-01-23 00:00:00 | 95033   | 3-105 | 計算機導論 |        92 | 王萍   |
| 104  | 李軍   | 1976-02-20 00:00:00 | 95033   | 3-105 | 計算機導論 |        89 | 王萍   |
| 105  | 王芳   | 1975-02-10 00:00:00 | 95031   | 3-105 | 計算機導論 |        88 | 王萍   |
| 109  | 趙鐵柱 | 1974-06-03 00:00:00 | 95031   | 3-105 | 計算機導論 |        76 | 王萍   |
| 103  | 王麗   | 1976-01-23 00:00:00 | 95033   | 3-245 | 操作系統   |        86 | 李誠   |
| 105  | 王芳   | 1975-02-10 00:00:00 | 95031   | 3-245 | 操作系統   |        75 | 李誠   |
| 109  | 趙鐵柱 | 1974-06-03 00:00:00 | 95031   | 3-245 | 操作系統   |        68 | 李誠   |
| 103  | 王麗   | 1976-01-23 00:00:00 | 95033   | 6-166 | 數字電路   |        85 | 張旭   |
| 105  | 王芳   | 1975-02-10 00:00:00 | 95031   | 6-166 | 數字電路   |        79 | 張旭   |
| 109  | 趙鐵柱 | 1974-06-03 00:00:00 | 95031   | 6-166 | 數字電路   |        81 | 張旭   |
+------+--------+---------------------+---------+-------+------------+-----------+--------+

24.查詢存在85分以上成績的課程c_no

輸入：

SELECT * FROM score where sc_degree > 85;

+------+-------+-----------+
| s_no | c_no  | sc_degree |
+------+-------+-----------+
| 101  | 3-105 |        90 |
| 102  | 3-105 |        91 |
| 103  | 3-105 |        92 |
| 103  | 3-245 |        86 |
| 104  | 3-105 |        89 |
| 105  | 3-105 |        88 |
+------+-------+-----------+

進階：知道c_no還不行,還需要看到c_name 以及對應的老師

SELECT sc.c_no,c.c_name, t.t_name 
FROM score AS sc, course AS c, teacher AS t 
WHERE sc.c_no IN(SELECT c_no FROM score where sc_degree > 85) AND sc.c_no = c.c_no AND c.t_no = t.t_no 
GROUP BY c.c_name;

+-------+------------+--------+
| c_no  | c_name     | t_name |
+-------+------------+--------+
| 3-105 | 計算機導論 | 王萍   |
| 3-245 | 操作系統   | 李誠   |
+-------+------------+--------+
--這兩位老師教出來的學生都有85分以上的

25.查出所有’計算機系’ 教師所教課程的成績表

首先查看教計算機系的老師id：

select * from teacher where t_depart='計算機系';

+------+--------+-------+---------------------+--------+----------+
| t_no | t_name | t_sex | t_birthday          | t_rof  | t_depart |
+------+--------+-------+---------------------+--------+----------+
| 804  | 李誠   | 男    | 1958-12-02 00:00:00 | 副教授 | 計算機系 |
| 825  | 王萍   | 女    | 1972-05-05 00:00:00 | 助教   | 計算機系 |
+------+--------+-------+---------------------+--------+----------+

根據老師id可以獲得班級id：

select * from course 
where t_no in (select t_no from teacher where t_depart='計算機系');

+-------+------------+------+
| c_no  | c_name     | t_no |
+-------+------------+------+
| 3-105 | 計算機導論 | 825  |
| 3-245 | 操作系統   | 804  |
+-------+------------+------+

根據班級id獲得成績：

SELECT * FROM score 
WHERE c_no 
IN (SELECT c_no FROM course WHERE t_no IN (SELECT t_no FROM teacher WHERE t_depart = '計算機系'));

+------+-------+-----------+
| s_no | c_no  | sc_degree |
+------+-------+-----------+
| 101  | 3-105 |        90 |
| 102  | 3-105 |        91 |
| 103  | 3-105 |        92 |
| 103  | 3-245 |        86 |
| 104  | 3-105 |        89 |
| 105  | 3-105 |        88 |
| 105  | 3-245 |        75 |
| 109  | 3-105 |        76 |
| 109  | 3-245 |        68 |
+------+-------+-----------+

進階：

SELECT  t.t_name,t.t_depart,c.c_name,s.s_name,s_class,sc.sc_degree 
FROM course AS c, score AS sc, teacher AS t,student AS s 
WHERE c.t_no 
IN (select t_no FROM teacher WHERE t_depart = '計算機系') AND c.t_no = t.t_no AND c.c_no = sc.c_no AND sc.s_no = s.s_no ;

+--------+----------+------------+--------+---------+-----------+
| t_name | t_depart | c_name     | s_name | s_class | sc_degree |
+--------+----------+------------+--------+---------+-----------+
| 王萍   | 計算機系 | 計算機導論 | 曾華   | 95033   |        90 |
| 王萍   | 計算機系 | 計算機導論 | 匡明   | 95031   |        91 |
| 王萍   | 計算機系 | 計算機導論 | 王麗   | 95033   |        92 |
| 王萍   | 計算機系 | 計算機導論 | 李軍   | 95033   |        89 |
| 王萍   | 計算機系 | 計算機導論 | 王芳   | 95031   |        88 |
| 王萍   | 計算機系 | 計算機導論 | 趙鐵柱 | 95031   |        76 |
| 李誠   | 計算機系 | 操作系統   | 王麗   | 95033   |        86 |
| 李誠   | 計算機系 | 操作系統   | 王芳   | 95031   |        75 |
| 李誠   | 計算機系 | 操作系統   | 趙鐵柱 | 95031   |        68 |
+--------+----------+------------+--------+---------+-----------+

26.查詢’計算機系’與’電子工程系’ 不同職稱的教師的name和rof

查詢計算機系中的職稱，且該職稱電子工程系沒有：

select * from teacher 
where t_depart='計算機系' and t_rof not in (select t_rof from teacher where t_depart='電子工程系');

+------+--------+-------+---------------------+--------+----------+
| t_no | t_name | t_sex | t_birthday          | t_rof  | t_depart |
+------+--------+-------+---------------------+--------+----------+
| 804  | 李誠   | 男    | 1958-12-02 00:00:00 | 副教授 | 計算機系 |
+------+--------+-------+---------------------+--------+----------+

同理，查詢電子工程系中的職稱，且該職稱計算機系沒有：

select * from teacher 
where t_depart='電子工程系' and t_rof not in (select t_rof from teacher where t_depart='計算機系');

+------+--------+-------+---------------------+-------+------------+
| t_no | t_name | t_sex | t_birthday          | t_rof | t_depart   |
+------+--------+-------+---------------------+-------+------------+
| 856  | 張旭   | 男    | 1969-03-12 00:00:00 | 講師  | 電子工程系 |
+------+--------+-------+---------------------+-------+------------+

使用union，拼接這兩個結果：

select * from teacher 
where t_depart='計算機系' and t_rof not in (select t_rof from teacher where t_depart='電子工程系')
union
select * from teacher 
where t_depart='電子工程系' and t_rof not in (select t_rof from teacher where t_depart='計算機系');

+------+--------+-------+---------------------+--------+------------+
| t_no | t_name | t_sex | t_birthday          | t_rof  | t_depart   |
+------+--------+-------+---------------------+--------+------------+
| 804  | 李誠   | 男    | 1958-12-02 00:00:00 | 副教授 | 計算機系   |
| 856  | 張旭   | 男    | 1969-03-12 00:00:00 | 講師   | 電子工程系 |
+------+--------+-------+---------------------+--------+------------+

27, 查詢選修編號爲"3-105"課程且成績至少高於選修編號爲’3-245’同學的c_no,s_no和sc_degree,並且按照sc_degree從高到地次序排序

select * from score 
where c_no = '3-105' 
AND sc_degree > ANY(SELECT sc_degree FROM score WHERE c_no = '3-245' ) 
ORDER BY sc_degree desc ;

+------+-------+-----------+
| s_no | c_no  | sc_degree |
+------+-------+-----------+
| 103  | 3-105 |        92 |
| 102  | 3-105 |        91 |
| 101  | 3-105 |        90 |
| 104  | 3-105 |        89 |
| 105  | 3-105 |        88 |
| 109  | 3-105 |        76 |
+------+-------+-----------+

28.查詢選修編號爲"3-105"且成績高於選修編號爲"3-245"課程的同學c_no.s_no和sc_degree

all表示所有。

SELECT * FROM score 
WHERE sc_degree > ALL (select sc_degree from score WHERE c_no = '3-245') 
AND c_no = '3-105';

+------+-------+-----------+
| s_no | c_no  | sc_degree |
+------+-------+-----------+
| 101  | 3-105 |        90 |
| 102  | 3-105 |        91 |
| 103  | 3-105 |        92 |
| 104  | 3-105 |        89 |
| 105  | 3-105 |        88 |
+------+-------+-----------+

進階：查出學生的信息,課程名稱,分數(s_name c_name,sc_degree)

SELECT s.s_name , c.c_name ,sc.sc_degree 
FROM score AS sc, student AS s,course AS c 
WHERE sc_degree > ALL (select sc_degree from score WHERE c.c_no = '3-245') 
AND c.c_no = '3-105' AND sc.s_no = s.s_no AND sc.c_no = c.c_no ;

+--------+------------+-----------+
| s_name | c_name     | sc_degree |
+--------+------------+-----------+
| 曾華   | 計算機導論 |        90 |
| 匡明   | 計算機導論 |        91 |
| 王麗   | 計算機導論 |        92 |
| 李軍   | 計算機導論 |        89 |
| 王芳   | 計算機導論 |        88 |
| 趙鐵柱 | 計算機導論 |        76 |
+--------+------------+-----------+

總結: ANY 和 ALL

ANY:表示任何一個就行了,如;數組A中的值比數組B中任何一個都要大,那麼只要A和B中最小的比較就行了.
ALL:表示所有都要比較,如:數組A中的值比數組B中所有的數都要大,那麼A要和B中最大的值比較才行

29. 查詢所有教師和同學的 name ,sex, birthday

SELECT s_name AS name, s_sex AS sex, s_birthday AS birthday  FROM student
UNION
SELECT t_name , t_sex , t_birthday  FROM teacher; --第二排會默認的匹配第一排

+--------+-----+---------------------+
| name   | sex | birthday            |
+--------+-----+---------------------+
| 曾華   | 男  | 1977-09-01 00:00:00 |
| 匡明   | 男  | 1975-10-02 00:00:00 |
| 王麗   | 女  | 1976-01-23 00:00:00 |
| 李軍   | 男  | 1976-02-20 00:00:00 |
| 王芳   | 女  | 1975-02-10 00:00:00 |
| 陸君   | 男  | 1974-06-03 00:00:00 |
| 王尼瑪 | 男  | 1976-02-20 00:00:00 |
| 張全蛋 | 男  | 1975-02-10 00:00:00 |
| 趙鐵柱 | 男  | 1974-06-03 00:00:00 |
| 張飛   | 男  | 1974-06-03 00:00:00 |
| 李誠   | 男  | 1958-12-02 00:00:00 |
| 王萍   | 女  | 1972-05-05 00:00:00 |
| 劉冰   | 女  | 1977-08-14 00:00:00 |
| 張旭   | 男  | 1969-03-12 00:00:00 |
+--------+-----+---------------------+

30.查詢所有’女’教師和’女’學生的name,sex,birthday

在上一部分加入限制條件where即可

SELECT s_name AS name, s_sex AS sex, s_birthday AS birthday  FROM student WHERE s_sex = '女'
UNION
SELECT t_name AS name, t_sex AS sex, t_birthday AS birthday FROM teacher WHERE t_sex = '女';

+------+-----+---------------------+
| name | sex | birthday            |
+------+-----+---------------------+
| 王麗 | 女  | 1976-01-23 00:00:00 |
| 王芳 | 女  | 1975-02-10 00:00:00 |
| 王萍 | 女  | 1972-05-05 00:00:00 |
| 劉冰 | 女  | 1977-08-14 00:00:00 |
+------+-----+---------------------+

31.查詢成績比該課程平均成績低的同學的成績表

首先查看各班級的平均成績：

select c_no, avg(sc_degree) from score
group by c_no;

+-------+----------------+
| c_no  | avg(sc_degree) |
+-------+----------------+
| 3-105 |        87.6667 |
| 3-245 |        76.3333 |
| 6-166 |        81.6667 |
+-------+----------------+

拆分來看，需要把成績表拆分成兩份，一份是原始成績，一份是計算的平均成績，然後以平均成績作爲篩選條件，在原始成績中找到比平均成績低的同學。

SELECT * FROM score AS sc1 /*原始成績表*/
WHERE sc1.sc_degree <  /*在獲取原始成績表中找到比平均成績低的id*/
(SELECT  AVG(sc_degree) FROM score AS sc2 /*平均成績表*/
WHERE sc1.c_no = sc2.c_no);/*id一致的同學*/

+------+-------+-----------+
| s_no | c_no  | sc_degree |
+------+-------+-----------+
| 105  | 3-245 |        75 |
| 105  | 6-166 |        79 |
| 109  | 3-105 |        76 |
| 109  | 3-245 |        68 |
| 109  | 6-166 |        81 |
+------+-------+-----------+

進階：顯示出學生name,課程name以及分數

SELECT s.s_name ,sc1.c_no,c.c_name, sc1.sc_degree 
FROM score AS sc1,student AS s,course AS c 
WHERE sc1.sc_degree < 
(SELECT  AVG(sc_degree) FROM score AS sc2 WHERE sc1.c_no = sc2.c_no) 
AND sc1.s_no = s.s_no AND sc1.c_no = c.c_no ;

+--------+-------+------------+-----------+
| s_name | c_no  | c_name     | sc_degree |
+--------+-------+------------+-----------+
| 王芳   | 3-245 | 操作系統   |        75 |
| 王芳   | 6-166 | 數字電路   |        79 |
| 趙鐵柱 | 3-105 | 計算機導論 |        76 |
| 趙鐵柱 | 3-245 | 操作系統   |        68 |
| 趙鐵柱 | 6-166 | 數字電路   |        81 |
+--------+-------+------------+-----------+

32.查詢所有任課教師的t_name 和 t_depart(要在分數表中可以查得到)

SELECT t_name,t_depart FROM teacher /*根據課程表老師的id獲取老師的信息*/
WHERE t_no IN(SELECT t_no FROM course);/*在課程表中獲取老師的id*/

+--------+------------+
| t_name | t_depart   |
+--------+------------+
| 李誠   | 計算機系   |
| 王萍   | 計算機系   |
| 劉冰   | 電子工程系 |
| 張旭   | 電子工程系 |
+--------+------------+

如果考慮有課程成績纔算任課的話：從score表中查出有過考試成績的課程,再用該課程查出教師的信息

SELECT * FROM teacher
WHERE t_no 
IN(SELECT t_no FROM course WHERE c_no IN (SELECT c_no from score));

+------+--------+-------+---------------------+--------+------------+
| t_no | t_name | t_sex | t_birthday          | t_rof  | t_depart   |
+------+--------+-------+---------------------+--------+------------+
| 804  | 李誠   | 男    | 1958-12-02 00:00:00 | 副教授 | 計算機系   |
| 825  | 王萍   | 女    | 1972-05-05 00:00:00 | 助教   | 計算機系   |
| 856  | 張旭   | 男    | 1969-03-12 00:00:00 | 講師   | 電子工程系 |
+------+--------+-------+---------------------+--------+------------+

33.查出至少有2名男生的班號

SELECT s_class FROM student 
WHERE s_sex = '男' 
GROUP BY s_class HAVING COUNT(s_no) > 1; 

+---------+
| s_class |
+---------+
| 95031   |
| 95033   |
+---------+

34.查詢student 表中不姓"王"的同學的記錄

SELECT * FROM student 
WHERE s_name NOT LIKE '王%';

+------+--------+-------+---------------------+---------+
| s_no | s_name | s_sex | s_birthday          | s_class |
+------+--------+-------+---------------------+---------+
| 101  | 曾華   | 男    | 1977-09-01 00:00:00 | 95033   |
| 102  | 匡明   | 男    | 1975-10-02 00:00:00 | 95031   |
| 104  | 李軍   | 男    | 1976-02-20 00:00:00 | 95033   |
| 106  | 陸君   | 男    | 1974-06-03 00:00:00 | 95031   |
| 108  | 張全蛋 | 男    | 1975-02-10 00:00:00 | 95031   |
| 109  | 趙鐵柱 | 男    | 1974-06-03 00:00:00 | 95031   |
| 110  | 張飛   | 男    | 1974-06-03 00:00:00 | 95038   |
+------+--------+-------+---------------------+---------+

35. 查詢student 中每個學生的姓名和年齡(當前時間 - 出生年份)

SELECT s_name, YEAR(NOW()) - YEAR(s_birthday) AS age FROM student;

+--------+------+
| s_name | age  |
+--------+------+
| 曾華   |   43 |
| 匡明   |   45 |
| 王麗   |   44 |
| 李軍   |   44 |
| 王芳   |   45 |
| 陸君   |   46 |
| 王尼瑪 |   44 |
| 張全蛋 |   45 |
| 趙鐵柱 |   46 |
| 張飛   |   46 |
+--------+------+

36. 查詢student中最大和最小的 s_birthday的值

SELECT MAX(s_birthday),MIN(s_birthday) FROM student;

+---------------------+---------------------+
| MAX(s_birthday)     | MIN(s_birthday)     |
+---------------------+---------------------+
| 1977-09-01 00:00:00 | 1974-06-03 00:00:00 |
+---------------------+---------------------+

37.以班級號和年齡從大到小的順序查詢student表中的全部記錄

SELECt * FROM student ORDER BY s_class DESC, s_birthday;

+------+--------+-------+---------------------+---------+
| s_no | s_name | s_sex | s_birthday          | s_class |
+------+--------+-------+---------------------+---------+
| 110  | 張飛   | 男    | 1974-06-03 00:00:00 | 95038   |
| 103  | 王麗   | 女    | 1976-01-23 00:00:00 | 95033   |
| 107  | 王尼瑪 | 男    | 1976-02-20 00:00:00 | 95033   |
| 104  | 李軍   | 男    | 1976-02-20 00:00:00 | 95033   |
| 101  | 曾華   | 男    | 1977-09-01 00:00:00 | 95033   |
| 109  | 趙鐵柱 | 男    | 1974-06-03 00:00:00 | 95031   |
| 106  | 陸君   | 男    | 1974-06-03 00:00:00 | 95031   |
| 105  | 王芳   | 女    | 1975-02-10 00:00:00 | 95031   |
| 108  | 張全蛋 | 男    | 1975-02-10 00:00:00 | 95031   |
| 102  | 匡明   | 男    | 1975-10-02 00:00:00 | 95031   |
+------+--------+-------+---------------------+---------+

38.查詢"男"教師及其所上的課

SELECT * FROM course 
WHERE t_no IN 
(SELECT t_no FROM teacher WHERE t_sex = '男');/*在teacher表查詢老師的id*/

+-------+----------+------+
| c_no  | c_name   | t_no |
+-------+----------+------+
| 3-245 | 操作系統 | 804  |
| 6-166 | 數字電路 | 856  |
+-------+----------+------+

進階:查出教師名稱,教師性別, 課程名字

SELECT t.t_name,t.t_sex ,c.c_name 
FROM teacher t ,course c 
WHERE t_sex = '男' AND t.t_no = c.t_no;

+--------+-------+----------+
| t_name | t_sex | c_name   |
+--------+-------+----------+
| 李誠   | 男    | 操作系統 |
| 張旭   | 男    | 數字電路 |
+--------+-------+----------+

39.查詢最高分同學的s_no c_no 和 sc_degree

SELECT * FROM score 
WHERE sc_degree = (select MAX(sc_degree) AS sc_degree FROM score);

+------+-------+-----------+
| s_no | c_no  | sc_degree |
+------+-------+-----------+
| 103  | 3-105 |        92 |
+------+-------+-----------+

40. 查詢和"李軍"同性別的所有同學的s_name

SELECT s_name, s_sex FROM student 
WHERE s_SEX = (SELECT s_sex FROM student WHERE s_name = '李軍');

+--------+-------+
| s_name | s_sex |
+--------+-------+
| 曾華   | 男    |
| 匡明   | 男    |
| 李軍   | 男    |
| 陸君   | 男    |
| 王尼瑪 | 男    |
| 張全蛋 | 男    |
| 趙鐵柱 | 男    |
| 張飛   | 男    |
+--------+-------+

41.查詢和"李軍"同性別並且同班的所有同學的s_name

SELECT s_name, s_sex FROM student 
WHERE s_sex = (SELECT s_sex FROM student WHERE s_name = '李軍') 
AND s_class = (SELECT s_class FROM student WHERE s_name = '李軍');
/*或者*/
SELECT s_name, s_sex FROM student s1 
WHERE s_sex = (SELECT s_sex FROM student s2 WHERE s_name = '李軍' 
               AND s1.s_class = s2.s_class);

+--------+-------+
| s_name | s_sex |
+--------+-------+
| 曾華   | 男    |
| 李軍   | 男    |
| 王尼瑪 | 男    |
+--------+-------+

42. 查詢所有選修’計算機導論’課程的’男’同學的成績表

SELECT * FROM score 
WHERE c_no = (SELECT c_no FROM course WHERE c_name = '計算機導論' ) 
AND s_no IN(SELECT s_no FROM student WHERE s_sex = '男');

+------+-------+-----------+
| s_no | c_no  | sc_degree |
+------+-------+-----------+
| 101  | 3-105 |        90 |
| 102  | 3-105 |        91 |
| 104  | 3-105 |        89 |
| 109  | 3-105 |        76 |
+------+-------+-----------+

進階：顯示出s_name,c_name 替代之前的 s_no 和 c_no

SELECT s_name,c_name,sc_degree 
FROM score,student,course 
WHERE score.c_no = (SELECT c_no FROM course WHERE c_name = '計算機導論' ) 
AND score.s_no IN(SELECT s_no FROM student WHERE s_sex = '男') 
AND score.s_no = student.s_no AND score.c_no = course.c_no ;

+--------+------------+-----------+
| s_name | c_name     | sc_degree |
+--------+------------+-----------+
| 曾華   | 計算機導論 |        90 |
| 匡明   | 計算機導論 |        91 |
| 李軍   | 計算機導論 |        89 |
| 趙鐵柱 | 計算機導論 |        76 |
+--------+------------+-----------+

43. 假設使用了以下命令建立了一個grade表

CREATE TABLE grade(
    low INT(3),
    upp INT(3),
    grade 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');

查詢所有同學的s_no , c_no 和grade列

SELECT s_no, c_no , grade FROM score, grade 
WHERE sc_degree BETWEEN low and upp; 

+------+-------+-------+
| s_no | c_no  | grade |
+------+-------+-------+
| 101  | 3-105 | A     |
| 102  | 3-105 | A     |
| 103  | 3-105 | A     |
| 103  | 3-245 | B     |
| 103  | 6-166 | B     |
| 104  | 3-105 | B     |
| 105  | 3-105 | B     |
| 105  | 3-245 | c     |
| 105  | 6-166 | c     |
| 109  | 3-105 | c     |
| 109  | 3-245 | D     |
| 109  | 6-166 | B     |
+------+-------+-------+

進階:顯示學生名字和課程名稱

SELECT  s.s_no, s.s_name, c.c_name ,c.c_no , grade 
FROM student s, course c ,score sc, grade 
WHERE sc_degree BETWEEN low and upp AND sc.s_no = s.s_no AND sc.c_no = c.c_no;

+------+--------+------------+-------+-------+
| s_no | s_name | c_name     | c_no  | grade |
+------+--------+------------+-------+-------+
| 101  | 曾華   | 計算機導論 | 3-105 | A     |
| 102  | 匡明   | 計算機導論 | 3-105 | A     |
| 103  | 王麗   | 計算機導論 | 3-105 | A     |
| 103  | 王麗   | 操作系統   | 3-245 | B     |
| 103  | 王麗   | 數字電路   | 6-166 | B     |
| 104  | 李軍   | 計算機導論 | 3-105 | B     |
| 105  | 王芳   | 計算機導論 | 3-105 | B     |
| 105  | 王芳   | 操作系統   | 3-245 | c     |
| 105  | 王芳   | 數字電路   | 6-166 | c     |
| 109  | 趙鐵柱 | 計算機導論 | 3-105 | c     |
| 109  | 趙鐵柱 | 操作系統   | 3-245 | D     |
| 109  | 趙鐵柱 | 數字電路   | 6-166 | B     |
+------+--------+------------+-------+-------+

MySQL數據庫使用筆記(三):查詢練習