MySQL经典练习题

表名和字段

–1.学生表 
Student(s_id,s_name,s_birth,s_sex) –学生编号,学生姓名, 出生年月,学生性别 
–2.课程表 
Course(c_id,c_name,t_id) – –课程编号, 课程名称, 教师编号 
–3.教师表 
Teacher(t_id,t_name) –教师编号,教师姓名 
–4.成绩表 
Score(s_id,c_id,s_score) –学生编号,课程编号,分数

测试数据

1.  
   --建表
2.  
   --学生表
3.  
   CREATE TABLE `Student`(
4.  
   `s_id` VARCHAR(20),
5.  
   `s_name` VARCHAR(20) NOT NULL DEFAULT '',
6.  
   `s_birth` VARCHAR(20) NOT NULL DEFAULT '',
7.  
   `s_sex` VARCHAR(10) NOT NULL DEFAULT '',
8.  
   PRIMARY KEY(`s_id`)
9.  
   );
10.  
    --课程表
11.  
    CREATE TABLE `Course`(
12.  
    `c_id` VARCHAR(20),
13.  
    `c_name` VARCHAR(20) NOT NULL DEFAULT '',
14.  
    `t_id` VARCHAR(20) NOT NULL,
15.  
    PRIMARY KEY(`c_id`)
16.  
    );
17.  
    --教师表
18.  
    CREATE TABLE `Teacher`(
19.  
    `t_id` VARCHAR(20),
20.  
    `t_name` VARCHAR(20) NOT NULL DEFAULT '',
21.  
    PRIMARY KEY(`t_id`)
22.  
    );
23.  
    --成绩表
24.  
    CREATE TABLE `Score`(
25.  
    `s_id` VARCHAR(20),
26.  
    `c_id` VARCHAR(20),
27.  
    `s_score` INT(3),
28.  
    PRIMARY KEY(`s_id`,`c_id`)
29.  
    );
30.  
    --插入学生表测试数据
31.  
    insert into Student values('01' , '赵雷' , '1990-01-01' , '男');
32.  
    insert into Student values('02' , '钱电' , '1990-12-21' , '男');
33.  
    insert into Student values('03' , '孙风' , '1990-05-20' , '男');
34.  
    insert into Student values('04' , '李云' , '1990-08-06' , '男');
35.  
    insert into Student values('05' , '周梅' , '1991-12-01' , '女');
36.  
    insert into Student values('06' , '吴兰' , '1992-03-01' , '女');
37.  
    insert into Student values('07' , '郑竹' , '1989-07-01' , '女');
38.  
    insert into Student values('08' , '王菊' , '1990-01-20' , '女');
39.  
    --课程表测试数据
40.  
    insert into Course values('01' , '语文' , '02');
41.  
    insert into Course values('02' , '数学' , '01');
42.  
    insert into Course values('03' , '英语' , '03');
43.  
     
44.  
    --教师表测试数据
45.  
    insert into Teacher values('01' , '张三');
46.  
    insert into Teacher values('02' , '李四');
47.  
    insert into Teacher values('03' , '王五');
48.  
     
49.  
    --成绩表测试数据
50.  
    insert into Score values('01' , '01' , 80);
51.  
    insert into Score values('01' , '02' , 90);
52.  
    insert into Score values('01' , '03' , 99);
53.  
    insert into Score values('02' , '01' , 70);
54.  
    insert into Score values('02' , '02' , 60);
55.  
    insert into Score values('02' , '03' , 80);
56.  
    insert into Score values('03' , '01' , 80);
57.  
    insert into Score values('03' , '02' , 80);
58.  
    insert into Score values('03' , '03' , 80);
59.  
    insert into Score values('04' , '01' , 50);
60.  
    insert into Score values('04' , '02' , 30);
61.  
    insert into Score values('04' , '03' , 20);
62.  
    insert into Score values('05' , '01' , 76);
63.  
    insert into Score values('05' , '02' , 87);
64.  
    insert into Score values('06' , '01' , 31);
65.  
    insert into Score values('06' , '03' , 34);
66.  
    insert into Score values('07' , '02' , 89);
67.  
    insert into Score values('07' , '03' , 98);

练习题和sql语句

1.  
   -- 1、查询"01"课程比"02"课程成绩高的学生的信息及课程分数
2.  
    
3. select a.* ,b.s_score as 01_score,c.s_score as 02_score from
4.  
   student a
5.  
   join score b on a.s_id=b.s_id and b.c_id='01'
6.  
   left join score c on a.s_id=c.s_id and c.c_id='02' or c.c_id = NULL where b.s_score>c.s_score
7.  
    
8. -- 2、查询"01"课程比"02"课程成绩低的学生的信息及课程分数
9.  
    
10. select a.* ,b.s_score as 01_score,c.s_score as 02_score from
11.  
    student a left join score b on a.s_id=b.s_id and b.c_id='01' or b.c_id=NULL
12.  
    join score c on a.s_id=c.s_id and c.c_id='02' where b.s_score<c.s_score
13.  
     
14.  
     
15.  
    -- 3、查询平均成绩大于等于60分的同学的学生编号和学生姓名和平均成绩
16.  解法一：
    select b.s_id,b.s_name,ROUND(AVG(a.s_score),2) as avg_score from
17. student b
18. join score a on b.s_id = a.s_id
19. GROUP BY b.s_id,b.s_name HAVING ROUND(AVG(a.s_score),2)>=60;
20.  
     解法二：
21.  select a.s_id,a.s_name,avg(b.s_score) from student a join score  b on a.s_id=b.s_id group by a.s_id having avg(b.s_score)>60;
     
22.  
    -- 4、查询平均成绩小于60分的同学的学生编号和学生姓名和平均成绩
23. -- (包括有成绩的和无成绩的)
24.  解法一：
     select a.s_id,a.s_name,avg(b.s_score) from student a left join score b on
25. a.s_id=b.s_id group by a.s_id having avg(b.s_score)<60 or avg(b.s_score) is null;
26.  
    解法二：

    select b.s_id,b.s_name,ROUND(AVG(a.s_score),2) as avg_score from
27. student b
28. left join score a on b.s_id = a.s_id
29. GROUP BY b.s_id,b.s_name HAVING ROUND(AVG(a.s_score),2)<60
30. union
31. select a.s_id,a.s_name,0 as avg_score from
32. student a
33. where a.s_id not in (
34. select distinct s_id from score);
35.  
     
36. -- 5、查询所有同学的学生编号、学生姓名、选课总数、所有课程的总成绩
37.  
    select a.s_id,a.s_name,count(b.c_id) as sum_course,sum(b.s_score) as sum_score from
38. student a
39. left join score b on a.s_id=b.s_id
40. GROUP BY a.s_id;
41.  
     
42. -- 6、查询"李"姓老师的数量
43.  
    select count(t_id) from teacher where t_name like '李%';
44.  
     
45.  
    -- 7、查询学过"张三"老师授课的同学的信息
46. 解法一： 
47.  
    select a.* from student a join score b on a.s_id=b.s_id join course c on b.c_id=c.c_id

    join teacher d on c.t_id=d.t_id and d.t_name='张三';

     

    解法二：

    select a.* from
48. student a
49. join score b on a.s_id=b.s_id where b.c_id in(
50. select c_id from course where t_id =(
51. select t_id from teacher where t_name = '张三'));
52.  
     
53. -- 8、查询没学过"张三"老师授课的同学的信息
54.  解法一：
    select * from
55. student c
56. where c.s_id not in(
57. select a.s_id from student a join score b on a.s_id=b.s_id where b.c_id in(
58. select c_id from course where t_id =(
59. select t_id from teacher where t_name = '张三')));

     

    解法二：

    select * from student a where a.s_id not in (select a.s_id from student a join score b on

    a.s_id=b.s_id join course c on b.c_id=c.c_id join teacher d on c.t_id=d.t_id and d.t_name='张三');
60.  
    -- 9、查询学过编号为"01"并且也学过编号为"02"的课程的同学的信息
61.  
     
62. select a.* from
63. student a,score b,score c
64. where a.s_id = b.s_id and a.s_id = c.s_id and b.c_id='01' and c.c_id='02';
65.  
     
66. -- 10、查询学过编号为"01"但是没有学过编号为"02"的课程的同学的信息
67.  
68. select a.* from
69. student a
70. where a.s_id in (select s_id from score where c_id='01' ) and a.s_id not in(select s_id from score where c_id='02')
71.   
72.  
    -- 11、查询没有学全所有课程的同学的信息
73.  
74. 解法一：
75.  
     select * from student a where a.s_id in (select b.s_id from score b group by b.s_id
76. having count(b.c_id)<3);
77.  
78. 解法二：
79.  
    select s.* from
80. student s where s.s_id in(
81. select s_id from score where s_id not in(
82. select a.s_id from score a
83. join score b on a.s_id = b.s_id and b.c_id='02'
84. join score c on a.s_id = c.s_id and c.c_id='03'
85. where a.c_id='01'))
86.  
87. -- 12、查询至少有一门课与学号为"01"的同学所学相同的同学的信息

    解法一：

     
88.  select distinct a.* from student a join score b on a.s_id=b.s_id where b.c_id in (select c_id from score where s_id='01') and b.s_id!='01';
89.  
    解法二：
90. select * from student where s_id in(
91. select distinct a.s_id from score a where a.c_id in

    (select a.c_id from score a where a.s_id='01'));
92.  
93. -- 13、查询和"01"号的同学学习的课程完全相同的其他同学的信息
94.  
95. select a.* from student a where a.s_id in(
96.  
    select distinct s_id from score where s_id!='01' and c_id in(select c_id from score where s_id='01')
97.  
    group by s_id
98.  
    having count(1)=(select count(1) from score where s_id='01'));
99.  
    -- 14、查询没学过"张三"老师讲授的任一门课程的学生姓名
100.  
     select a.s_name from student a where a.s_id not in (
101.  
     select s_id from score where c_id =
102.  
     (select c_id from course where t_id =(
103.  
     select t_id from teacher where t_name = '张三'))
104.  
     group by s_id);
105.  
      
106.  
     -- 15、查询两门及其以上不及格课程的同学的学号，姓名及其平均成绩
107.  
     select a.s_id,a.s_name,ROUND(AVG(b.s_score)) from
108.  
     student a
109.  
     left join score b on a.s_id = b.s_id
110.  
     where a.s_id in(
111.  
     select s_id from score where s_score<60 GROUP BY s_id having count(1)>=2)
112.  
     GROUP BY a.s_id,a.s_name
113.  
      
114.  
     -- 16、检索"01"课程分数小于60，按分数降序排列的学生信息
115.  
     select a.*,b.c_id,b.s_score from
116.  
     student a,score b
117.  
     where a.s_id = b.s_id and b.c_id='01' and b.s_score<60 ORDER BY b.s_score DESC;
118.  
      
119.  
     -- 17、按平均成绩从高到低显示所有学生的所有课程的成绩以及平均成绩
120.  
     select a.s_id,(select s_score from score where s_id=a.s_id and c_id='01') as 语文,
121.  
     (select s_score from score where s_id=a.s_id and c_id='02') as 数学,
122.  
     (select s_score from score where s_id=a.s_id and c_id='03') as 英语,
123.  
     round(avg(s_score),2) as 平均分 from score a GROUP BY a.s_id ORDER BY 平均分 DESC;
124.  
      
125.  
     -- 18.查询各科成绩最高分、最低分和平均分：以如下形式显示：课程ID，课程name，最高分，最低分，平均分，及格率，中等率，优良率，优秀率
126.  
     --及格为>=60，中等为：70-80，优良为：80-90，优秀为：>=90
127.  
     select a.c_id,b.c_name,MAX(s_score),MIN(s_score),ROUND(AVG(s_score),2),
128.  
     ROUND(100*(SUM(case when a.s_score>=60 then 1 else 0 end)/SUM(case when a.s_score then 1 else 0 end)),2) as 及格率,
129.  
     ROUND(100*(SUM(case when a.s_score>=70 and a.s_score<=80 then 1 else 0 end)/SUM(case when a.s_score then 1 else 0 end)),2) as 中等率,
130.  
     ROUND(100*(SUM(case when a.s_score>=80 and a.s_score<=90 then 1 else 0 end)/SUM(case when a.s_score then 1 else 0 end)),2) as 优良率,
131.  
     ROUND(100*(SUM(case when a.s_score>=90 then 1 else 0 end)/SUM(case when a.s_score then 1 else 0 end)),2) as 优秀率
132.  
     from score a left join course b on a.c_id = b.c_id GROUP BY a.c_id,b.c_name
133.  
      
134.  
     -- 19、按各科成绩进行排序，并显示排名(实现不完全)
135.  
     -- mysql没有rank函数
136.  
     select a.s_id,a.c_id,
137.  
     @i:=@i +1 as i保留排名,
138.  
     @k:=(case when @score=a.s_score then @k else @i end) as rank不保留排名,
139.  
     @score:=a.s_score as score
140.  
     from (
141.  
     select s_id,c_id,s_score from score WHERE c_id='01' GROUP BY s_id,c_id,s_score ORDER BY s_score DESC
142.  
     )a,(select @k:=0,@i:=0,@score:=0)s
143.  
     union
144.  
     select a.s_id,a.c_id,
145.  
     @i:=@i +1 as i,
146.  
     @k:=(case when @score=a.s_score then @k else @i end) as rank,
147.  
     @score:=a.s_score as score
148.  
     from (
149.  
     select s_id,c_id,s_score from score WHERE c_id='02' GROUP BY s_id,c_id,s_score ORDER BY s_score DESC
150.  
     )a,(select @k:=0,@i:=0,@score:=0)s
151.  
     union
152.  
     select a.s_id,a.c_id,
153.  
     @i:=@i +1 as i,
154.  
     @k:=(case when @score=a.s_score then @k else @i end) as rank,
155.  
     @score:=a.s_score as score
156.  
     from (
157.  
     select s_id,c_id,s_score from score WHERE c_id='03' GROUP BY s_id,c_id,s_score ORDER BY s_score DESC
158.  
     )a,(select @k:=0,@i:=0,@score:=0)s
159.  
      
160.  
     -- 20、查询学生的总成绩并进行排名
161.  
     select a.s_id,
162.  
     @i:=@i+1 as i,
163.  
     @k:=(case when @score=a.sum_score then @k else @i end) as rank,
164.  
     @score:=a.sum_score as score
165.  
     from (select s_id,SUM(s_score) as sum_score from score GROUP BY s_id ORDER BY sum_score DESC)a,
166.  
     (select @k:=0,@i:=0,@score:=0)s
167.  
      
168.  
     -- 21、查询不同老师所教不同课程平均分从高到低显示
169.  
      
170.  
     select a.t_id,c.t_name,a.c_id,ROUND(avg(s_score),2) as avg_score from course a
171.  
     left join score b on a.c_id=b.c_id
172.  
     left join teacher c on a.t_id=c.t_id
173.  
     GROUP BY a.c_id,a.t_id,c.t_name ORDER BY avg_score DESC;
174.  
     -- 22、查询所有课程的成绩第2名到第3名的学生信息及该课程成绩
175.  
      
176.  
     select d.*,c.排名,c.s_score,c.c_id from (
177.  
     select a.s_id,a.s_score,a.c_id,@i:=@i+1 as 排名 from score a,(select @i:=0)s where a.c_id='01'
178.  
     )c
179.  
     left join student d on c.s_id=d.s_id
180.  
     where 排名 BETWEEN 2 AND 3
181.  
     UNION
182.  
     select d.*,c.排名,c.s_score,c.c_id from (
183.  
     select a.s_id,a.s_score,a.c_id,@j:=@j+1 as 排名 from score a,(select @j:=0)s where a.c_id='02'
184.  
     )c
185.  
     left join student d on c.s_id=d.s_id
186.  
     where 排名 BETWEEN 2 AND 3
187.  
     UNION
188.  
     select d.*,c.排名,c.s_score,c.c_id from (
189.  
     select a.s_id,a.s_score,a.c_id,@k:=@k+1 as 排名 from score a,(select @k:=0)s where a.c_id='03'
190.  
     )c
191.  
     left join student d on c.s_id=d.s_id
192.  
     where 排名 BETWEEN 2 AND 3;
193.  
      
194.  
      
195.  
     -- 23、统计各科成绩各分数段人数：课程编号,课程名称,[100-85],[85-70],[70-60],[0-60]及所占百分比
196.  
      
197.  
      
198.  
     select distinct f.c_name,a.c_id,b.`85-100`,b.百分比,c.`70-85`,c.百分比,d.`60-70`,d.百分比,e.`0-60`,e.百分比 from score a
199.  
     left join (select c_id,SUM(case when s_score >85 and s_score <=100 then 1 else 0 end) as `85-100`,
200.  
     ROUND(100*(SUM(case when s_score >85 and s_score <=100 then 1 else 0 end)/count(*)),2) as 百分比
201.  
     from score GROUP BY c_id)b on a.c_id=b.c_id
202.  
     left join (select c_id,SUM(case when s_score >70 and s_score <=85 then 1 else 0 end) as `70-85`,
203.  
     ROUND(100*(SUM(case when s_score >70 and s_score <=85 then 1 else 0 end)/count(*)),2) as 百分比
204.  
     from score GROUP BY c_id)c on a.c_id=c.c_id
205.  
     left join (select c_id,SUM(case when s_score >60 and s_score <=70 then 1 else 0 end) as `60-70`,
206.  
     ROUND(100*(SUM(case when s_score >60 and s_score <=70 then 1 else 0 end)/count(*)),2) as 百分比
207.  
     from score GROUP BY c_id)d on a.c_id=d.c_id
208.  
     left join (select c_id,SUM(case when s_score >=0 and s_score <=60 then 1 else 0 end) as `0-60`,
209.  
     ROUND(100*(SUM(case when s_score >=0 and s_score <=60 then 1 else 0 end)/count(*)),2) as 百分比
210.  
     from score GROUP BY c_id)e on a.c_id=e.c_id
211.  
     left join course f on a.c_id = f.c_id
212.  
      
213.  
     -- 24、查询学生平均成绩及其名次
214.  
      
215.  
     select a.s_id,
216.  
     @i:=@i+1 as '不保留空缺排名',
217.  
     @k:=(case when @avg_score=a.avg_s then @k else @i end) as '保留空缺排名',
218.  
     @avg_score:=avg_s as '平均分'
219.  
     from (select s_id,ROUND(AVG(s_score),2) as avg_s from score GROUP BY s_id)a,(select @avg_score:=0,@i:=0,@k:=0)b;
220.  
     -- 25、查询各科成绩前三名的记录
221.  
     -- 1.选出b表比a表成绩大的所有组
222.  
     -- 2.选出比当前id成绩大的 小于三个的
223.  
     select a.s_id,a.c_id,a.s_score from score a
224.  
     left join score b on a.c_id = b.c_id and a.s_score<b.s_score
225.  
     group by a.s_id,a.c_id,a.s_score HAVING COUNT(b.s_id)<3
226.  
     ORDER BY a.c_id,a.s_score DESC
227.  
      
228.  
     -- 26、查询每门课程被选修的学生数
229.  
      
230.  
     select c_id,count(s_id) from score a GROUP BY c_id
231.  
      
232.  
     -- 27、查询出只有两门课程的全部学生的学号和姓名
233.  
     select s_id,s_name from student where s_id in(
234.  
     select s_id from score GROUP BY s_id HAVING COUNT(c_id)=2);
235.  
      
236.  
     -- 28、查询男生、女生人数
237.  
     select s_sex,COUNT(s_sex) as 人数 from student GROUP BY s_sex
238.  
      
239.  
     -- 29、查询名字中含有"风"字的学生信息
240.  
      
241.  
     select * from student where s_name like '%风%';
242.  
      
243.  
     -- 30、查询同名同性学生名单，并统计同名人数
244.  
      
245.  
     select a.s_name,a.s_sex,count(*) from student a JOIN
246.  
     student b on a.s_id !=b.s_id and a.s_name = b.s_name and a.s_sex = b.s_sex
247.  
     GROUP BY a.s_name,a.s_sex
248.  
      
249.  
      
250.  
      
251.  
     -- 31、查询1990年出生的学生名单
252.  
      
253.  
     select s_name from student where s_birth like '1990%'
254.  
      
255.  
     -- 32、查询每门课程的平均成绩，结果按平均成绩降序排列，平均成绩相同时，按课程编号升序排列
256.  
      
257.  
     select c_id,ROUND(AVG(s_score),2) as avg_score from score GROUP BY c_id ORDER BY avg_score DESC,c_id ASC
258.  
      
259.  
     -- 33、查询平均成绩大于等于85的所有学生的学号、姓名和平均成绩
260.  
      
261.  
     select a.s_id,b.s_name,ROUND(avg(a.s_score),2) as avg_score from score a
262.  
     left join student b on a.s_id=b.s_id GROUP BY s_id HAVING avg_score>=85
263.  
      
264.  
     -- 34、查询课程名称为"数学"，且分数低于60的学生姓名和分数
265.  
      
266.  
     select a.s_name,b.s_score from score b LEFT JOIN student a on a.s_id=b.s_id where b.c_id=(
267.  
     select c_id from course where c_name ='数学') and b.s_score<60
268.  
      
269.  
     -- 35、查询所有学生的课程及分数情况；
270.  
      
271.  
      
272.  
     select a.s_id,a.s_name,
273.  
     SUM(case c.c_name when '语文' then b.s_score else 0 end) as '语文',
274.  
     SUM(case c.c_name when '数学' then b.s_score else 0 end) as '数学',
275.  
     SUM(case c.c_name when '英语' then b.s_score else 0 end) as '英语',
276.  
     SUM(b.s_score) as '总分'
277.  
     from student a left join score b on a.s_id = b.s_id
278.  
     left join course c on b.c_id = c.c_id
279.  
     GROUP BY a.s_id,a.s_name
280.  
      
281.  
      
282.  
     -- 36、查询任何一门课程成绩在70分以上的姓名、课程名称和分数；
283.  
     select a.s_name,b.c_name,c.s_score from course b left join score c on b.c_id = c.c_id
284.  
     left join student a on a.s_id=c.s_id where c.s_score>=70
285.  
      
286.  
      
287.  
      
288.  
     -- 37、查询不及格的课程
289.  
     select a.s_id,a.c_id,b.c_name,a.s_score from score a left join course b on a.c_id = b.c_id
290.  
     where a.s_score<60
291.  
      
292.  
     --38、查询课程编号为01且课程成绩在80分以上的学生的学号和姓名；
293.  
     select a.s_id,b.s_name from score a LEFT JOIN student b on a.s_id = b.s_id
294.  
     where a.c_id = '01' and a.s_score>80
295.  
      
296.  
     -- 39、求每门课程的学生人数
297.  
     select count(*) from score GROUP BY c_id;
298.  
      
299.  
     -- 40、查询选修"张三"老师所授课程的学生中，成绩最高的学生信息及其成绩
300.  
      
301.  
      
302.  
     -- 查询老师id
303.  
     select c_id from course c,teacher d where c.t_id=d.t_id and d.t_name='张三'
304.  
     -- 查询最高分（可能有相同分数）
305.  
     select MAX(s_score) from score where c_id='02'
306.  
     -- 查询信息
307.  
     select a.*,b.s_score,b.c_id,c.c_name from student a
308.  
     LEFT JOIN score b on a.s_id = b.s_id
309.  
     LEFT JOIN course c on b.c_id=c.c_id
310.  
     where b.c_id =(select c_id from course c,teacher d where c.t_id=d.t_id and d.t_name='张三')
311.  
     and b.s_score in (select MAX(s_score) from score where c_id='02')
312.  
      
313.  
      
314.  
     -- 41、查询不同课程成绩相同的学生的学生编号、课程编号、学生成绩
315.  
     select DISTINCT b.s_id,b.c_id,b.s_score from score a,score b where a.c_id != b.c_id and a.s_score = b.s_score
316.  
      
317.  
      
318.  
     -- 42、查询每门功成绩最好的前两名
319.  
     -- 牛逼的写法
320.  
     select a.s_id,a.c_id,a.s_score from score a
321.  
     where (select COUNT(1) from score b where b.c_id=a.c_id and b.s_score>=a.s_score)<=2 ORDER BY a.c_id
322.  
      
323.  
      
324.  
     -- 43、统计每门课程的学生选修人数（超过5人的课程才统计）。要求输出课程号和选修人数，查询结果按人数降序排列，若人数相同，按课程号升序排列
325.  
     select c_id,count(*) as total from score GROUP BY c_id HAVING total>5 ORDER BY total,c_id ASC
326.  
      
327.  
     -- 44、检索至少选修两门课程的学生学号
328.  
     select s_id,count(*) as sel from score GROUP BY s_id HAVING sel>=2
329.  
      
330.  
     -- 45、查询选修了全部课程的学生信息
331.  
     select * from student where s_id in(
332.  
     select s_id from score GROUP BY s_id HAVING count(*)=(select count(*) from course))
333.  
      
334.  
      
335.  
     --46、查询各学生的年龄
336.  
     -- 按照出生日期来算，当前月日 < 出生年月的月日则，年龄减一
337.  
      
338.  
     select s_birth,(DATE_FORMAT(NOW(),'%Y')-DATE_FORMAT(s_birth,'%Y') -
339.  
     (case when DATE_FORMAT(NOW(),'%m%d')>DATE_FORMAT(s_birth,'%m%d') then 0 else 1 end)) as age
340.  
     from student;
341.  
      
342.  
      
343.  
     -- 47、查询本周过生日的学生
344.  
     select * from student where WEEK(DATE_FORMAT(NOW(),'%Y%m%d'))=WEEK(s_birth)
345.  
     select * from student where YEARWEEK(s_birth)=YEARWEEK(DATE_FORMAT(NOW(),'%Y%m%d'))
346.  
      
347.  
     select WEEK(DATE_FORMAT(NOW(),'%Y%m%d'))
348.  
      
349.  
     -- 48、查询下周过生日的学生
350.  
     select * from student where WEEK(DATE_FORMAT(NOW(),'%Y%m%d'))+1 =WEEK(s_birth)
351.  
      
352.  
     -- 49、查询本月过生日的学生
353.  
      
354.  
     select * from student where MONTH(DATE_FORMAT(NOW(),'%Y%m%d')) =MONTH(s_birth)
355.  
      
356.  
     -- 50、查询下月过生日的学生
357.  
     select * from student where MONTH(DATE_FORMAT(NOW(),'%Y%m%d'))+1 =MONTH(s_birth)