SQL經典五十道題

漏船載酒發表於2017-11-01
SQL

–1.學生表
Student(S,Sname,Sage,Ssex) –S 學生編號,Sname 學生姓名,Sage 出生年月,Ssex 學生性別
–2.課程表 
Course(C,Cname,T) –C –課程編號,Cname 課程名稱,T 教師編號
–3.教師表 
Teacher(T,Tname) –T 教師編號,Tname 教師姓名
–4.成績表 
SC(S,C,score) –S 學生編號,C 課程編號,score 分數
*/
–建立測試資料

create table Student(S varchar(10),Sname varchar(10),Sage datetime,Ssex nvarchar(10))
insert into Student values(`01` , `趙雷` , `1990-01-01` , `男`)
insert into Student values(`02` , `錢電` , `1990-12-21` , `男`)
insert into Student values(`03` , `孫風` , `1990-05-20` , `男`)
insert into Student values(`04` , `李雲` , `1990-08-06` , `男`)
insert into Student values(`05` , `周梅` , `1991-12-01` , `女`)
insert into Student values(`06` , `吳蘭` , `1992-03-01` , `女`)
insert into Student values(`07` , `鄭竹` , `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` , `語文` , `02`)
insert into Course values(`02` , `數學` , `01`)
insert into Course values(`03` , `英語` , `03`)
create table Teacher(T varchar(10),Tname,varchar(10))
insert into Teacher values(`01` , `張三`)
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、查詢”01″課程比”02″課程成績高的學生的資訊及課程分數

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、查詢”01″課程比”02″課程成績低的學生的資訊及課程分數

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、查詢平均成績大於等於60分的同學的學生編號和學生姓名和平均成績

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、查詢平均成績小於60分的同學的學生編號和學生姓名和平均成績

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、查詢所有同學的學生編號、學生姓名、選課總數、所有課程的總成績

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、查詢”李”姓老師的數量 

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

–7、查詢學過”張三”老師授課的同學的資訊 

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=`張三`)

–8、查詢沒學過”張三”老師授課的同學的資訊 

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 =`張三`))

–9、查詢學過編號為”01″並且也學過編號為”02″的課程的同學的資訊

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、查詢學過編號為”01″但是沒有學過編號為”02″的課程的同學的資訊

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、查詢沒有學全所有課程的同學的資訊 

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、查詢至少有一門課與學號為”01″的同學所學相同的同學的資訊 

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、查詢和”01″號的同學學習的課程完全相同的其他同學的資訊 

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、查詢沒學過”張三”老師講授的任一門課程的學生姓名 

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=`張三`
) a
,sc b
WHERE
a.c=b.C
)

–15、查詢兩門及其以上不及格課程的同學的學號，姓名及其平均成績 

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、檢索”01″課程分數小於60，按分數降序排列的學生資訊

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、按平均成績從高到低顯示所有學生的所有課程的成績以及平均成績

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、查詢各科成績最高分、最低分和平均分：以如下形式顯示：課程ID，課程name，最高分，最低分，平均分，及格率，中等率，優良率，優秀率
–及格為>=60，中等為：70-80，優良為：80-90，優秀為：>=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、按各科成績進行排序，並顯示排名

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、查詢學生的總成績並進行排名

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、查詢不同老師所教不同課程平均分從高到低顯示 

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、查詢所有課程的成績第2名到第3名的學生資訊及該課程成績

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、統計各科成績各分數段人數：課程編號,課程名稱,[100-85],[85-70],[70-60],[0-60]及所佔百分比 

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、查詢學生平均成績及其名次 

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、查詢各科成績前三名的記錄

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、查詢每門課程被選修的學生數 

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

–27、查詢出只有兩門課程的全部學生的學號和姓名  

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、查詢男生、女生人數 

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

–29、查詢名字中含有”風”字的學生資訊

SELECT
*
,count(*)
FROM student 
WHERE
Sname rLIKE `風`

–30、查詢同名同性學生名單，並統計同名人數 

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

–31、查詢1990年出生的學生名單(注：Student表中Sage列的型別是datetime) 

SELECT
*
FROM
student
WHERE
Sage LIKE `1990%`

–32、查詢每門課程的平均成績，結果按平均成績降序排列，平均成績相同時，按課程編號

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、查詢平均成績大於等於85的所有學生的學號、姓名和平均成績 

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、查詢課程名稱為”數學”，且分數低於60的學生姓名和分數 

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

–35、查詢所有學生的課程及分數情況；

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

–36、查詢任何一門課程成績在70分以上的姓名、課程名稱和分數； 

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、查詢不及格的課程

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、查詢課程編號為01且課程成績在80分以上的學生的學號和姓名； 

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、求每門課程的學生人數 

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

–40、查詢選修”張三”老師所授課程的學生中，成績最高的學生資訊及其成績

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 =`張三`

–41、查詢不同課程成績相同的學生的學生編號、課程編號、學生成績 

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

–42、查詢每門功成績最好的前兩名 

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、統計每門課程的學生選修人數（超過5人的課程才統計）。要求輸出課程號和選修人數，查詢結果按人數降序排列，若人數相同，按課程號升序排列  

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、檢索至少選修兩門課程的學生學號 

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

–45、查詢選修了全部課程的學生資訊 

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

–46、查詢各學生的年齡

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

–47、查詢本週過生日的學生

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

–48、查詢下週過生日的學生

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

–49、查詢本月過生日的學生

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

–50、查詢下月過生日的學生

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

其中有三四個題做的不盡人意勉強實現需求


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