--1.学生表
Student(S,Sname,Sage,Ssex) --S 学生编号,Sname 学生姓名,Sage 出生年月,Ssex 学生性别
--2.课程表
Course(C,Cname,T) --C --课程编号,Cname 课程名称,T 教师编号
--3.教师表
Teacher(T,Tname) --T 教师编号,Tname 教师姓名
--4.成绩表
SC(S,C,score) --S 学生编号,C 课程编号,score 分数
*/
--创建测试数据

create table Student(S varchar(10),Sname varchar(10),Sage datetime,Ssex nvarchar(10))
insert into Student values('01' , '赵雷' , '1990-01-01' , '男')
insert into Student values('02' , '钱电' , '1990-12-21' , '男')
insert into Student values('03' , '孙风' , '1990-05-20' , '男')
insert into Student values('04' , '李云' , '1990-08-06' , '男')
insert into Student values('05' , '周梅' , '1991-12-01' , '女')
insert into Student values('06' , '吴兰' , '1992-03-01' , '女')
insert into Student values('07' , '郑竹' , '1989-07-01' , '女')
insert into Student values('08' , '王菊' , '1990-01-20' , '女')
create table Course(C varchar(10),Cname,varchar(10),T varchar(10))
insert into Course values('01' , '语文' , '02')
insert into Course values('02' , '数学' , '01')
insert into Course values('03' , '英语' , '03')
create table Teacher(T varchar(10),Tname,varchar(10))
insert into Teacher values('01' , '张三')
insert into Teacher values('02' , '李四')
insert into Teacher values('03' , '王五')
create table SC(S varchar(10),C varchar(10),score decimal(18,1))
insert into SC values('01' , '01' , 80)
insert into SC values('01' , '02' , 90)
insert into SC values('01' , '03' , 99)
insert into SC values('02' , '01' , 70)
insert into SC values('02' , '02' , 60)
insert into SC values('02' , '03' , 80)
insert into SC values('03' , '01' , 80)
insert into SC values('03' , '02' , 80)
insert into SC values('03' , '03' , 80)
insert into SC values('04' , '01' , 50)
insert into SC values('04' , '02' , 30)
insert into SC values('04' , '03' , 20)
insert into SC values('05' , '01' , 76)
insert into SC values('05' , '02' , 87)
insert into SC values('06' , '01' , 31)
insert into SC values('06' , '03' , 34)
insert into SC values('07' , '02' , 89)
insert into SC values('07' , '03' , 98)

--1、查询"01"课程比"02"课程成绩高的学生的信息及课程分数

SELECT a.* ,c.* 
from 
(select 
    a.*    
    from
(SELECT * from sc WHERE sc.C in('01'))a
left JOIN(SELECT * from sc where sc.C in('02'))b
ON a.s =b.s 
where a.score>b.score ) a ,student c
where a.s =c.s;

--2、查询"01"课程比"02"课程成绩低的学生的信息及课程分数

SELECT a.* ,c.*
FROM
(SELECT a.*
FROM
(SELECT * FROM sc WHERE sc.C in('01'))a
LEFT JOIN(SELECT * FROM sc WHERE sc.C in('02'))b
ON a.s =b.s WHERE a.score<b.score) a,student c
WHERE a.s =c.s

--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

SELECT
b.s
,c.Sname
,b.avgscore
FROM
(SELECT 
    a.s s
    , avg(a.score) avgscore
FROM sc a
GROUP BY a.s) b
    ,student c
WHERE
b.avgscore>60 AND c.s =b.s

--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

SELECT
b.s
,c.Sname
,b.avgscore
FROM
(SELECT 
    a.s s
    , avg(a.score) avgscore
FROM sc a
GROUP BY a.s) b
    ,student c
WHERE
b.avgscore<60 AND c.s =b.s

--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

SELECT
    b.s
    ,c.Sname
    ,b.num
    ,b.sumscore
    FROM
(SELECT
    a.s s
    ,COUNT(a.c) num 
    ,SUM(a.score) sumscore
FROM 
    sc a
GROUP BY a.s) b
    ,student c
WHERE b.s =c.s

--6、查询"李"姓老师的数量

SELECT
COUNT(a.Tname)
FROM
(SELECT
    Tname Tname
FROM
    teacher
    WHERE
    Tname LIKE '李%') a

--7、查询学过"张三"老师授课的同学的信息

SELECT
d.*
FROM
student d
,sc e
WHERE
e.S =d.S
AND
e.C=
(SELECT
    b.C
FROM
    teacher a
    ,course b
WHERE
    a.T =b.T AND a.Tname='张三')

--8、查询没学过"张三"老师授课的同学的信息

SELECT
a.*
FROM
student a
WHERE
a.S NOT in 
(SELECT 
 b.S
FROM
sc a
,student b

WHERE
a.S=b.S AND
a.C =
(SELECT
    b.c 
FROM
    teacher a
    ,course b
WHERE
    a.T =b.T AND a.Tname ='张三'))

--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

SELECT
*
FROM 
sc a,
sc b,
student c
WHERE
a.S =b.S AND a.C='01' and b.C='02'    
AND c.S =a.S

--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

SELECT
*
FROM
student a
WHERE
a.S in
(
SELECT
DISTINCT(sc.s)
FROM
sc
WHERE
sc.S
NOT
in(
SELECT S
FROM sc
WHERE
 sc.C in('02')
GROUP BY
sc.S)
)

--11、查询没有学全所有课程的同学的信息

SELECT
b.*
FROM
student b
WHERE
b.S in
(
SELECT
a.s
FROM
(SELECT
    a.S s
    ,COUNT(a.C) NUM
FROM
sc a
GROUP BY
a.s) a
WHERE
a.NUM<3
)

--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

SELECT
e.*
FROM
student e
WHERE
e.S in 
(SELECT
DISTINCT(c.s)
FROM
student c
,sc d
WHERE
c.s=d.s
AND 
d.C in 
(SELECT 
b.c
FROM 
student a
,sc  b
WHERE
a.s =b.s AND a.s ='01'
)
)

--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

SELECT
    a.c
FROM
    sc a    
WHERE
    a.S ='01'                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       

---

SELECT
*
FROM
(SELECT
a.*
,COUNT(b.c) num
FROM
student a
,sc b
WHERE
a.s=b.S 
GROUP BY
b.S
) a
WHERE
a.num=3 AND a.s <> '01'

--14、查询没学过"张三"老师讲授的任一门课程的学生姓名

SELECT
*
FROM
student a
WHERE
a.S NOT in 
(
SELECT
b.S
FROM
(
SELECT
b.c 
,b.Cname
FROM
teacher a
,course b
WHERE
a.T=b.T
AND
a.Tname='张三'
) a
,sc b
WHERE
a.c=b.C
)

--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

SELECT
b.S
,b.Sname
,a.avgscore
FROM
(SELECT
AVG(score) avgscore
,s S
FROM
sc
WHERE
sc.score<60
GROUP BY
s
HAVING COUNT(s)>=2) a
,student b
WHERE
a.S=b.S

--16、检索"01"课程分数小于60，按分数降序排列的学生信息

SELECT
b.*
FROM
(SELECT
a.s s
FROM
sc a
WHERE
a.C ='01'
AND
a.score<60
ORDER BY a.score DESC
) a
,student b
WHERE
a.s=b.S

--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

SELECT
*
FROM
(SELECT
b.S
,b.C
,b.score
,c.avgscore
FROM
sc b
LEFT JOIN
(SELECT
a.S
,AVG(a.score) avgscore
FROM
sc a
GROUP BY a.S) c
ON c.S =b.S) a
,student b
WHERE
a.S =b.S
ORDER BY avgscore DESC

--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
--及格为>=60，中等为：70-80，优良为：80-90，优秀为：>=90

SELECT
a.C
,b.Cname
,MAX(a.score)
,MIN(a.score)
,AVG(a.score)
,(SELECT COUNT(1) FROM sc WHERE sc.C=b.C and score>60)/(SELECT COUNT(1)FROM sc WHERE sc.C=b.c ) jigelv
FROM sc a ,course b 
WHERE a.C =b.C
GROUP BY
a.C

SELECT
a.C
,a.Cname
,MAX(b.score)
,MIN(b.score)
,CAST(AVG(b.score) AS DECIMAL(18,2)) pingqunfen
,CAST((SELECT COUNT(1) FROM sc WHERE sc.C=a.C AND sc.score>60)/
(SELECT COUNT(1) FROM sc WHERE sc.C =a.C) AS DECIMAL(18,2)) jigelv
,CAST((SELECT COUNT(1) FROM sc WHERE sc.C =a.c AND sc.score>=70 AND sc.score<80)/
(SELECT COUNT(1) FROM sc WHERE sc.c =a.c) AS DECIMAL (18,2)) youlianlv
FROM
course a,sc b
WHERE
a.C=b.C
GROUP BY a.C,a.Cname
ORDER BY a.C DESC

--19、按各科成绩进行排序，并显示排名

SELECT 
c.s
,c.sname
,b.cname
,a.score
,(SELECT COUNT(1) FROM sc WHERE sc.C=a.c AND sc.score > a.score)+1 mc
FROM 
sc a ,course b,student c 
WHERE a.c='01'
AND a.c=b.c 
AND a.s=c.s
ORDER BY mc

SELECT 
c.s
,c.sname
,b.cname
,a.score
,(SELECT COUNT(1) FROM sc WHERE sc.C=a.c AND sc.score > a.score)+1 mc
FROM 
sc a ,course b,student c 
WHERE a.c='02'
AND a.c=b.c 
AND a.s=c.s
ORDER BY mc

SELECT 
c.s
,c.sname
,b.cname
,a.score
,(SELECT COUNT(1) FROM sc WHERE sc.C=a.c AND sc.score > a.score)+1 mc
FROM 
sc a ,course b,student c 
WHERE a.c='03'
AND a.c=b.c 
AND a.s=c.s
ORDER BY mc

--20、查询学生的总成绩并进行排名

SELECT 
b.s
,b.sumscore
,@rownum:=@rownum +1 AS rownum
FROM
(SELECT
a.s s
,SUM(a.score) sumscore
FROM
sc a
GROUP BY
a.S
ORDER BY sumscore DESC
) as b
,(SELECT @rownum:=0)r

--21、查询不同老师所教不同课程平均分从高到低显示

SELECT
c.Tname
,b.Cname
,AVG(a.score) 
FROM
sc a
,course b
,teacher c
WHERE
a.C =b.C
AND b.T =c.T
GROUP BY a.C
ORDER BY AVG(a.score) DESC

--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

SELECT
a.*
,b.*
FROM
(SELECT b.s ,b.C ,b.score
,(SELECT COUNT(*) FROM sc a WHERE a.c='01'AND a.score>b.score)+1 mc
FROM sc b  WHERE b.c='01' HAVING mc BETWEEN 2 AND 3
UNION ALL
SELECT b.s ,b.C ,b.score
,(SELECT COUNT(*) FROM sc a WHERE a.c='02'AND a.score>b.score)+1 mc
FROM sc b  WHERE b.c='02' HAVING mc BETWEEN 2 AND 3
UNION ALL
SELECT b.s ,b.C ,b.score
,(SELECT COUNT(*) FROM sc a WHERE a.c='03'AND a.score>b.score)+1 mc
FROM sc b  WHERE b.c='03' HAVING mc BETWEEN 2 AND 3
) a
,student b
WHERE
a.s =b.s

--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

SELECT
a.*
FROM
(SELECT
c.Cname
,(SELECT COUNT(*)FROM sc a WHERE a.score>85 AND a.C=b.c AND c.c=a.C AND  a.C='01') '85以上'
,(SELECT COUNT(*)FROM sc a WHERE a.score<85 AND a.C=b.c AND c.c=a.C AND a.score>70 AND a.C='01') '[70_85]'
,(SELECT COUNT(*)FROM sc a WHERE a.score>70 AND a.C=b.c  AND c.c=a.C AND a.score>60 AND a.C='01') '[60_70]'
,(SELECT COUNT(*)FROM sc a WHERE a.score<60 AND a.C=b.c  AND c.c=a.C AND a.C='01') '60一下'
,(SELECT COUNT(*)FROM sc a WHERE a.score>85 AND a.C=b.c  AND c.c=a.C AND a.C='01')/(SELECT COUNT(*)FROM sc WHERE c='01'AND C=b.c AND c.c=c) '85以上比率'
,(SELECT COUNT(*)FROM sc a WHERE a.score<85 AND a.C=b.c  AND c.c=a.C AND a.score>70 AND a.C='01')/(SELECT COUNT(*)FROM sc WHERE c='01'AND C=b.c AND c.c=c) '[70_85]以上比率'
,(SELECT COUNT(*)FROM sc a WHERE a.score>70 AND a.C=b.c  AND c.c=a.C AND a.score>60 AND a.C='01')/(SELECT COUNT(*)FROM sc WHERE c='01'AND C=b.c AND c.c=c)'[60_70]以上比率'
,(SELECT COUNT(*)FROM sc a WHERE a.score<60 AND a.C=b.c AND c.c=a.C  AND a.C='01')/(SELECT COUNT(*)FROM sc WHERE c='01'AND C=b.c AND c.c=c)'60以上比率'
FROM sc b ,course c WHERE b.c=c.c AND c.c='01'
UNION ALL
SELECT
c.Cname
,(SELECT COUNT(*)FROM sc a WHERE a.score>85 AND a.C=b.c AND c.c=a.C AND  a.C='02') '85以上'
,(SELECT COUNT(*)FROM sc a WHERE a.score<85 AND a.C=b.c AND c.c=a.C AND a.score>70 AND a.C='02') '[70_85]'
,(SELECT COUNT(*)FROM sc a WHERE a.score>70 AND a.C=b.c  AND c.c=a.C AND a.score>60 AND a.C='02') '[60_70]'
,(SELECT COUNT(*)FROM sc a WHERE a.score<60 AND a.C=b.c  AND c.c=a.C AND a.C='02') '60一下'
,(SELECT COUNT(*)FROM sc a WHERE a.score>85 AND a.C=b.c  AND c.c=a.C AND a.C='02')/(SELECT COUNT(*)FROM sc WHERE c='02'AND C=b.c AND c.c=c) '85以上比率'
,(SELECT COUNT(*)FROM sc a WHERE a.score<85 AND a.C=b.c  AND c.c=a.C AND a.score>70 AND a.C='02')/(SELECT COUNT(*)FROM sc WHERE c='02'AND C=b.c AND c.c=c)'[70_85]以上比率'
,(SELECT COUNT(*)FROM sc a WHERE a.score>70 AND a.C=b.c  AND c.c=a.C AND a.score>60 AND a.C='02')/(SELECT COUNT(*)FROM sc WHERE c='02'AND C=b.c AND c.c=c)'[60_70]以上比率'
,(SELECT COUNT(*)FROM sc a WHERE a.score<60 AND a.C=b.c AND c.c=a.C  AND a.C='02')/(SELECT COUNT(*)FROM sc WHERE c='02'AND C=b.c AND c.c=c)'60以上比率'
FROM sc b ,course c WHERE b.c=c.c AND c.c='02'
UNION ALL
SELECT
c.Cname
,(SELECT COUNT(*)FROM sc a WHERE a.score>85 AND a.C=b.c AND c.c=a.C AND  a.C='03') '85以上'
,(SELECT COUNT(*)FROM sc a WHERE a.score<85 AND a.C=b.c AND c.c=a.C AND a.score>70 AND a.C='03') '[70_85]'
,(SELECT COUNT(*)FROM sc a WHERE a.score>70 AND a.C=b.c  AND c.c=a.C AND a.score>60 AND a.C='03') '[60_70]'
,(SELECT COUNT(*)FROM sc a WHERE a.score<60 AND a.C=b.c  AND c.c=a.C AND a.C='03') '60一下'
,(SELECT COUNT(*)FROM sc a WHERE a.score>85 AND a.C=b.c  AND c.c=a.C AND a.C='03')/(SELECT COUNT(*)FROM sc WHERE c='03'AND C=b.c AND c.c=c) '85以上比率'
,(SELECT COUNT(*)FROM sc a WHERE a.score<85 AND a.C=b.c  AND c.c=a.C AND a.score>70 AND a.C='03')/(SELECT COUNT(*)FROM sc WHERE c='03'AND C=b.c AND c.c=c)'[70_85]以上比率'
,(SELECT COUNT(*)FROM sc a WHERE a.score>70 AND a.C=b.c  AND c.c=a.C AND a.score>60 AND a.C='03')/(SELECT COUNT(*)FROM sc WHERE c='03'AND C=b.c AND c.c=c)'[60_70]以上比率'
,(SELECT COUNT(*)FROM sc a WHERE a.score<60 AND a.C=b.c AND c.c=a.C  AND a.C='01')/(SELECT COUNT(*)FROM sc WHERE c='03'AND C=b.c AND c.c=c)'60以上比率'
FROM sc b ,course c WHERE b.c=c.c AND c.c='03') a

--24、查询学生平均成绩及其名次

SELECT
a.s
,a.avgscore
,@rownum:=@rownum +1 AS rownum
FROM 
(SELECT
s
,AVG(score) avgscore
FROM
sc 
GROUP BY s
ORDER BY avgscore DESC
) a
,(SELECT @rownum:=0)r

--25、查询各科成绩前三名的记录

SELECT
a.*
,b.*
FROM
(SELECT b.s ,b.C ,b.score
,(SELECT COUNT(*) FROM sc a WHERE a.c='01'AND a.score>b.score)+1 mc
FROM sc b  WHERE b.c='01' HAVING mc BETWEEN 1 AND 3
UNION ALL
SELECT b.s ,b.C ,b.score
,(SELECT COUNT(*) FROM sc a WHERE a.c='02'AND a.score>b.score)+1 mc
FROM sc b  WHERE b.c='02' HAVING mc BETWEEN 1 AND 3
UNION ALL
SELECT b.s ,b.C ,b.score
,(SELECT COUNT(*) FROM sc a WHERE a.c='03'AND a.score>b.score)+1 mc
FROM sc b  WHERE b.c='03' HAVING mc BETWEEN 1 AND 3
) a
,student b
WHERE
a.s =b.s

--26、查询每门课程被选修的学生数

SELECT
a.Cname
,COUNT(b.c)
FROM sc b,course a 
WHERE a.c =b.c
GROUP BY b.c

--27、查询出只有两门课程的全部学生的学号和姓名

SELECT
b.S
,b.Sname
,a.countc
FROM
(SELECT
s 
,COUNT(c) countc
FROM 
sc
GROUP BY s
HAVING countc =2) a
,student b
WHERE
a.s=b.s

--28、查询男生、女生人数

select s.Ssex,COUNT(*)from student s where s.Ssex='男'
UNION
select s.Ssex,COUNT(*)from student s where s.Ssex='女'

--29、查询名字中含有"风"字的学生信息

SELECT
*
,count(*)
FROM student 
WHERE
Sname rLIKE '风'

--30、查询同名同性学生名单，并统计同名人数

SELECT
s.Sname
,s.Ssex
,COUNT(*) countnum
from
student s
GROUP BY
s.Sname,s.Ssex
HAVING
countnum>=2

--31、查询1990年出生的学生名单(注：Student表中Sage列的类型是datetime)

SELECT
*
FROM
student
WHERE
Sage LIKE '1990%'

--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

SELECT
a.Cname
,AVG(sc.score) avgscore
FROM sc ,course a
WHERE sc.C =a.C
GROUP BY sc.C
ORDER BY avgscore DESC

--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

SELECT
*
FROM
(SELECT
a.Sname
,a.S
,AVG(sc.score) avgscore
FROM sc ,student a
WHERE sc.s =a.s 
GROUP BY sc.s
ORDER BY avgscore DESC
) a
WHERE
a.avgscore>85

--34、查询课程名称为"数学"，且分数低于60的学生姓名和分数

SELECT
*
FROM
sc a,course b
WHERE 
a.c =b.c AND b.Cname='数学' AND a.score>60

--35、查询所有学生的课程及分数情况；

SELECT
*
FROM
student a
,course b
,sc c
WHERE
a.S=c.S AND b.C =c.C

--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；

SELECT
b.Sname
,c.Cname
,a.score
FROM
sc  a, student b,course c
WHERE
a.score>70 AND a.C =c.C AND a.S =b.S

--37、查询不及格的课程

SELECT
b.Sname
,c.Cname
,a.score
FROM
sc  a, student b,course c
WHERE
a.score<60 AND a.C =c.C AND a.S =b.S

--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；

SELECT
c.S
,c.Sname
,a.Cname
,b.score
FROM
course a ,sc b ,student c
WHERE a.C =b.C AND b.score>=80 AND c.S =b.S AND a.C='01'

--39、求每门课程的学生人数

SELECT
b.Cname
,COUNT(a.c)
FROM
sc a ,course b
WHERE
b.c=a.C
GROUP BY
a.C

--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

SELECT
b.*
,MAX(c.score)
FROM
teacher a,student b ,sc c ,course d
WHERE
a.T =d.T AND d.C =c.C AND c.S =b.S AND  a.Tname ='张三'

--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

SELECT c.* FROM sc c GROUP BY c.`C`,c.`score` HAVING COUNT(*)>1;

--42、查询每门功成绩最好的前两名

SELECT
a.*
,b.*
FROM
(SELECT b.s ,b.C ,b.score
,(SELECT COUNT(*) FROM sc a WHERE a.c='01'AND a.score>b.score)+1 mc
FROM sc b  WHERE b.c='01' HAVING mc BETWEEN 1 AND 2
UNION ALL
SELECT b.s ,b.C ,b.score
,(SELECT COUNT(*) FROM sc a WHERE a.c='02'AND a.score>b.score)+1 mc
FROM sc b  WHERE b.c='02' HAVING mc BETWEEN 1 AND 2
UNION ALL
SELECT b.s ,b.C ,b.score
,(SELECT COUNT(*) FROM sc a WHERE a.c='03'AND a.score>b.score)+1 mc
FROM sc b  WHERE b.c='03' HAVING mc BETWEEN 1 AND 2
) a
,student b
WHERE
a.s =b.s

--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

SELECT
b.C
,b.Cname 
,COUNT(a.C) countc
FROM
sc a,course b
WHERE
a.c=b.C 
GROUP BY
a.C
HAVING countc>5
ORDER BY countc DESC

--44、检索至少选修两门课程的学生学号

SELECT
sc.S
,COUNT(sc.C) countc
FROM
sc
GROUP BY sc.S
HAVING countc >=2

--45、查询选修了全部课程的学生信息

SELECT
a.*
,COUNT(sc.C) countc
FROM
sc ,student  a
WHERE sc.S =a.S
GROUP BY sc.S
HAVING countc =3

--46、查询各学生的年龄

SELECT
    s.s,
    s.sname,
    EXTRACT(YEAR FROM NOW())-EXTRACT(YEAR FROM s.sage) 年龄
FROM
    student s

--47、查询本周过生日的学生

SELECT
s.S
,s.Sname
,s.Sage
FROM student s
WHERE YEARWEEK(DATE_FORMAT(s.Sage,'%Y-%m-%d')) =YEARWEEK(NOW())

--48、查询下周过生日的学生

SELECT
s.S
,s.Sname
,s.Sage
FROM student s
WHERE YEARWEEK(DATE_FORMAT(s.Sage,'%Y-%m-%d')) =YEARWEEK(NOW())+1

--49、查询本月过生日的学生

SELECT
s.S
,s.Sname
,s.Sage
FROM student s
WHERE MONTH(DATE_FORMAT(s.Sage,'%Y-%m-%d')) =MONTH(NOW())

--50、查询下月过生日的学生

SELECT
s.S
,s.Sname
,s.Sage
FROM student s
WHERE MONTH(DATE_FORMAT(s.Sage,'%Y-%m-%d')) =MONTH(NOW())+1

SQL 经典五十道题

其中有三四个题做的不尽人意勉强实现需求

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