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SQL語句加强練習（MySQL8.0為例）
2022-07-04 03:36:00 【Cancri e】
數據錶介紹
- 學生錶
Student(SId,Sname,Sage,Ssex)
SId 學生編號,Sname 學生姓名,Sage 出生年月,Ssex 學生性別
- 課程錶
Course(CId,Cname,TId)
CId 課程編號,Cname 課程名稱,TId 教師編號
- 教師錶
Teacher(TId,Tname)
TId 教師編號,Tname 教師姓名
- 成績錶
SC(SId,CId,score)
SId 學生編號,CId 課程編號,score 分數
SQL語句
- 學生錶 Student
create table Student(SId varchar(10),Sname varchar(10),Sage datetime,Ssex varchar(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' , '1990-12-20' , '男');
insert into Student values('04' , '李雲' , '1990-12-06' , '男');
insert into Student values('05' , '周梅' , '1991-12-01' , '女');
insert into Student values('06' , '吳蘭' , '1992-01-01' , '女');
insert into Student values('07' , '鄭竹' , '1989-01-01' , '女');
insert into Student values('09' , '張三' , '2017-12-20' , '女');
insert into Student values('10' , '李四' , '2017-12-25' , '女');
insert into Student values('11' , '李四' , '2012-06-06' , '女');
insert into Student values('12' , '趙六' , '2013-06-13' , '女');
insert into Student values('13' , '孫七' , '2014-06-01' , '女');- 課程錶 Course
create table Course(CId varchar(10),Cname nvarchar(10),TId 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');- 教師錶 Teacher
create table Teacher(TId 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');- 成績錶 SC
create table SC(SId varchar(10),CId 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);練習題目
查詢" 0 "課程比" 02 "課程成績高的學生的信息及課程分數
SQL語句
SELECT s.*, s1.CId, s1.score, s2.CId, s2.score
FROM Student as s, SC as s1, SC as s2
WHERE s.SId = s1.SId AND s.SId = s2.SId AND
s1.CId = '01' AND s2.CId = '02' AND
s1.score > s2.score
結果
查詢同時存在" 01 "課程和" 02 "課程的情况
SQL語句
SELECT s1.*, s2.CId, s2.score
FROM SC as s1, SC as s2
WHERE s1.SId = s2.SId AND
s1.CId = '01' AND s2.CId = '02'
結果
查詢存在" 01 "課程但可能不存在" 02 "課程的情况(不存在時顯示為 null )
SQL語句
SELECT s1.*, s2.CId,s2.score
FROM( SELECT *
FROM SC
WHERE SC.CId = '01') AS s1
LEFT JOIN (SELECT *
FROM SC
WHERE SC.CId = '02') AS s2
ON s1.SId = s2.SId
結果
查詢不存在" 01 "課程但存在" 02 "課程的情况
SQL語句
SELECT s2.SId, s1.CId, s1.score, s2.CId, s2.score
FROM( SELECT *
FROM SC
WHERE SC.CId = '01') AS s1
RIGHT JOIN (SELECT *
FROM SC
WHERE SC.CId = '02') AS s2
ON s1.SId = s2.SId
結果
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
SQL語句
SELECT s.SId, s.Sname, a.average_score
FROM (SELECT SId, AVG(score) as average_score
FROM SC
GROUP BY SId) as a
LEFT JOIN Student as s
ON a.SId = s.SId
WHERE a.average_score >= 60
結果
查詢在 SC 錶存在成績的學生信息
SQL語句
SELECT *
FROM Student
WHERE SId in (SELECT DISTINCT SId
FROM SC)
結果
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(沒成績的顯示為 null)
SQL語句
SELECT s.SId, s.Sname, a.course_num, a.sorce_sum
FROM Student as s
LEFT JOIN (SELECT SId, COUNT(CId) AS course_num, SUM(score) AS sorce_sum
FROM SC
GROUP BY SId) AS a
ON s.SId = a.SId
結果
查詢「李」姓老師的數量
SQL語句
SELECT COUNT(*) AS li_num
FROM Teacher
WHERE Tname LIKE '李%'
結果
查詢學過「張三」老師授課的同學的信息
SQL語句
SELECT s.*
FROM Student as s
WHERE SId IN (SELECT SId
FROM SC
WHERE CId IN (SELECT CId
FROM Course
WHERE TId IN (SELECT TId
FROM Teacher
WHERE Tname = '張三')))
結果
查詢沒有學全所有課程的同學的信息
SQL語句
SELECT *
FROM Student
WHERE SId IN (SELECT SId
FROM SC
GROUP BY SId
HAVING COUNT(CId) < (SELECT COUNT(*)
FROM Course) )
結果
查詢至少有一門課與學號為" 01 "的同學所學相同的同學的信息
SQL語句
SELECT *
FROM Student
WHERE SId IN (SELECT DISTINCT SId
FROM SC
WHERE CId IN (SELECT CId
FROM SC
WHERE SId = '01') AND SId != '01')
結果
查詢和" 0 "號的同學學習的課程完全相同的其他同學的信息
SQL語句
SELECT *
FROM Student
WHERE SId IN (SELECT DISTINCT SId
FROM SC
WHERE CId IN (SELECT CId
FROM SC
WHERE SId = '01') AND SId != '01'
GROUP BY SId
HAVING COUNT(CId)>=3)
結果
查詢沒學過"張三"老師講授的任一門課程的學生姓名
SQL語句
SELECT Sname
FROM Student
WHERE SId NOT IN (SELECT SId
FROM SC
WHERE CId IN(SELECT CId
FROM Course
WHERE TId IN (SELECT TId
FROM Teacher
WHERE Tname = '張三')))
結果
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
SQL語句
SELECT s.SId, s.Sname, AVG(score)
FROM Student as s, SC
WHERE s.SId = SC.SId AND score < 60
GROUP BY SC.SId
HAVING COUNT(*) >= 2
結果
檢索" 0 "課程分數小於 60，按分數降序排列的學生信息
SQL語句
SELECT s.*, score
FROM Student as s, SC
WHERE CId = '01' AND score < 60 AND s.SId = SC.SId
ORDER BY score DESC
結果
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
SQL語句
SELECT SId,
SUM(CASE WHEN CId = '01' THEN score ELSE NULL END) AS score_01,
SUM(CASE WHEN CId = '02' THEN score ELSE NULL END) AS score_02,
SUM(CASE WHEN CId = '03' THEN score ELSE NULL END) AS score_03,
AVG(score) AS average_score
FROM SC
GROUP BY SId
ORDER BY average_score DESC
結果
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。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，按課程號昇序排列
SQL語句
SELECT c.CId AS '課程ID',
c.Cname AS '課程name',
MAX(score) AS '最高分',
MIN(score) AS '最低分',
AVG(score) AS '平均分',
SUM(CASE WHEN score>=60 THEN 1 ELSE 0 END)/COUNT(*) AS '及格率',
SUM(CASE WHEN score>=70 AND score<80 THEN 1 ELSE 0 END)/COUNT(*) AS '中等率',
SUM(CASE WHEN score>=80 AND score<90 THEN 1 ELSE 0 END)/COUNT(*) AS '優良率',
SUM(CASE WHEN score>=90 THEN 1 ELSE 0 END)/COUNT(*) AS '優秀率'
FROM SC, Course AS c
WHERE SC.CId = c.CId
GROUP BY c.CId
ORDER BY COUNT(*) DESC, c.CId ASC
結果
按各科成績進行排序，並顯示排名， Score 重複時保留名次空缺
SQL語句
SELECT s.*, rank_01, rank_02, rank_03
FROM Student as s
LEFT JOIN ( SELECT SId, rank() OVER ( PARTITION BY CId ORDER BY score DESC ) AS rank_01 FROM SC WHERE CId = 01 ) a ON s.SId = a.SId
LEFT JOIN ( SELECT SId, rank() OVER ( PARTITION BY CId ORDER BY score DESC ) AS rank_02 FROM SC WHERE CId = 02 ) b ON s.SId = b.SId
LEFT JOIN ( SELECT SId, rank() OVER ( PARTITION BY CId ORDER BY score DESC ) AS rank_03 FROM SC WHERE CId = 03 ) c ON s.SId = c.Sid
結果
按各科成績進行排序，並顯示排名， Score 重複時合並名次
SQL語句
SELECT s.*, rank_01, rank_02, rank_03
FROM Student as s
LEFT JOIN ( SELECT SId, dense_rank() OVER ( PARTITION BY CId ORDER BY score DESC ) AS rank_01 FROM SC WHERE CId = 01 ) a ON s.SId = a.SId
LEFT JOIN ( SELECT SId, dense_rank() OVER ( PARTITION BY CId ORDER BY score DESC ) AS rank_02 FROM SC WHERE CId = 02 ) b ON s.SId = b.SId
LEFT JOIN ( SELECT SId, dense_rank() OVER ( PARTITION BY CId ORDER BY score DESC ) AS rank_03 FROM SC WHERE CId = 03 ) c ON s.SId = c.Sid
結果
查詢學生的總成績，並進行排名，總分重複時保留名次空缺
SQL語句
SELECT s.*, rank_total
FROM Student as s
LEFT JOIN (SELECT SId, rank() OVER (ORDER BY AVG(score) DESC) AS rank_total FROM SC GROUP BY SId) a ON s.SId = a.SId
ORDER BY rank_total ASC
結果
查詢學生的總成績，並進行排名，總分重複時不保留名次空缺
SQL語句
SELECT s.*, rank_total
FROM Student as s
LEFT JOIN (SELECT SId, dense_rank() OVER (ORDER BY AVG(score) DESC) AS rank_total FROM SC GROUP BY SId) a ON s.SId = a.SId
ORDER BY rank_total ASC
結果
統計各科成績各分數段人數：課程編號，課程名稱，[00-85]，[85-70]，[70-60]，[60-0] 及所占百分比
SQL語句
SELECT c.CId AS '課程編號',
Cname AS '課程名稱',
a.*
FROM Course as c,
(SELECT CId,
SUM(CASE WHEN score>=85 AND score<=100 THEN 1 ELSE 0 END)/COUNT(*) AS '100_85',
SUM(CASE WHEN score>=70 AND score<85 THEN 1 ELSE 0 END)/COUNT(*) AS '85_70',
SUM(CASE WHEN score>=60 AND score<70 THEN 1 ELSE 0 END)/COUNT(*) AS '70_60',
SUM(CASE WHEN score>=0 AND score<60 THEN 1 ELSE 0 END)/COUNT(*) AS '60_0'
FROM SC
GROUP BY CId) as a
WHERE a.CId = c.CId
結果
查詢各科成績前三名的記錄
SQL語句
SELECT *
FROM (SELECT *, rank() OVER(PARTITION BY CId ORDER BY score DESC) AS rank_three
FROM SC) as a
WHERE a.rank_three<=3
ORDER BY a.CId, a.rank_three
結果
查詢每門課程被選修的學生數
SQL語句
SELECT c.CId, Cname, COUNT(*) AS '選修人數'
FROM SC, Course as c
WHERE SC.CId = c.CId
GROUP BY CId
結果
查詢出只選修兩門課程的學生學號和姓名
SQL語句
SELECT s.SId, Sname
FROM SC, Student as s
WHERE SC.SId = s.SId
GROUP BY s.SId
HAVING COUNT(*) = 2
結果
查詢男生、女生人數
SQL語句
SELECT Ssex, COUNT(*)
FROM Student
GROUP BY Ssex
結果
查詢名字中含有「風」字的學生信息
SQL語句
SELECT *
FROM Student
WHERE Sname LIKE '%風%'
結果
查詢同名同性學生名單，並統計同名人數
SQL語句
SELECT s.*, a.num
FROM Student as s
LEFT JOIN (SELECT Sname, Ssex, COUNT(*) AS num
FROM Student
GROUP BY Sname, Ssex) AS a
ON a.Sname = s.Sname
WHERE
a.num>1
結果
查詢 990 年出生的學生名單
查詢 990 年出生的學生名單SQL語句
SELECT Sname, Sage
FROM Student
WHERE Sage LIKE '1990%'
結果
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，按課程編號昇序排列
SQL語句
SELECT CId, AVG(score) AS average_score
FROM SC
GROUP BY CId
ORDER BY AVG(score) DESC, CId ASC
結果
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
SQL語句
SELECT s.SId, Sname, AVG(score) AS average_score
FROM SC, Student as s
WHERE SC.SId = s.SId
GROUP BY SC.SId
HAVING average_score>=85
結果
查詢課程名稱為「數學」，且分數低於 60 的學生姓名和分數
SQL語句
SELECT s.Sname, score
FROM Student as s, Course as c, SC
WHERE s.SId = SC.SId AND SC.CId = c.CId AND c.Cname = '數學'
HAVING score<60
結果
查詢所有學生的課程及分數情况（存在學生沒成績，沒選課的情况）
SQL語句
SELECT s.*, score, c.Cname
FROM Student as s
LEFT JOIN SC ON SC.SId = s.SId
LEFT JOIN Course as c ON SC.CId = c.CId
結果
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
SQL語句
SELECT Sname, Cname, score
FROM Student as s, SC, Course as c
WHERE s.SId = SC.SId AND SC.CId = c.CId
HAVING score>70
結果
查詢不及格的課程
SQL語句
SELECT Sname, Cname
FROM Student as s, SC, Course as c
WHERE s.SId = SC.SId AND SC.CId = c.CId AND score<60
結果
查詢課程編號為 0 且課程成績在 80 分以上的學生的學號和姓名
SQL語句
SELECT s.SId, Sname
FROM Student as s, SC
WHERE SC.SId = s.SId AND SC.CId = '01' AND score>=80
結果
求每門課程的學生人數
SQL語句
SELECT CId, COUNT(*) AS '學生人數'
FROM SC
GROUP BY CId
結果
成績不重複，查詢選修「張三」老師所授課程的學生中，成績最高的學生信息及其成績
SQL語句
SELECT s.*, a.Cname, a.max_score
FROM Student as s,
(SELECT SId, c.Cname, MAX(score) AS max_score
FROM SC, Course as c, Teacher as t
WHERE t.Tname = '張三' AND t.TId = c.TId AND
c.CId = SC.CId) as a
WHERE a.SId = s.SId
結果
成績有重複的情况下，查詢選修「張三」老師所授課程的學生中，成績最高的學生信息及其成績
SQL語句
SELECT s.*, b.score, b.ranking
FROM Student as s,
(SELECT SC.SId, SC.score, dense_rank() OVER(ORDER BY score DESC) AS ranking
FROM SC
WHERE CId = (SELECT CId
FROM Course
WHERE TId = (SELECT TId
FROM Teacher
WHERE Tname = '張三'))) AS b
WHERE b.ranking = 1 AND b.SId = s.SId
結果
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(有點小問題)
SQL語句
SELECT s1.*, s2.*
FROM SC as s1 JOIN SC as s2
WHERE s1.CId != s2.CId AND s1.score = s2.score AND s1.SId != s2.SId
ORDER BY s1.SId, s1.CId, s1.score
結果
查詢每門功成績最好的前兩名
SQL語句
SELECT *
FROM (SELECT *, rank() OVER(PARTITION BY CId ORDER BY score DESC) AS rank_two
FROM SC) as a
WHERE a.rank_two<=2
ORDER BY a.CId, a.rank_two
結果
統計每門課程的學生選修人數（超過 5 人的課程才統計）
SQL語句
SELECT CId, COUNT(*) AS course_num
FROM SC
GROUP BY CId
HAVING course_num>5
結果
檢索至少選修兩門課程的學生學號
SQL語句
SELECT SId, COUNT(*) AS course_num
FROM SC
GROUP BY SId
HAVING course_num>=2
結果
查詢選修了全部課程的學生信息
SQL語句
SELECT *
FROM Student
WHERE SId IN(SELECT SId
FROM SC
GROUP BY SId
HAVING COUNT(*) = (SELECT COUNT(*) FROM Course))
結果
查詢各學生的年齡，只按年份來算
SQL語句
SELECT Sname, YEAR(NOW())-YEAR(Sage) AS age
FROM Student
結果
按照出生日期來算，當前月日 < 出生年月的月日則，年齡减一
SQL語句
SELECT Sname, TIMESTAMPDIFF(YEAR,Sage,NOW()) AS age
FROM Student
結果
查詢本周過生日的學生
SQL語句
SELECT *
FROM Student
WHERE WEEK(NOW()) = WEEK(Sage)
結果
查詢下周過生日的學生
SQL語句
SELECT *
FROM Student
WHERE WEEK(NOW())+1 = WEEK(Sage)
結果
查詢本月過生日的學生
SQL語句
SELECT *
FROM Student
WHERE MONTH(NOW()) =MONTH(Sage)
結果
查詢下月過生日的學生
SQL語句
SELECT *
FROM Student
WHERE MONTH(NOW())+1 =MONTH(Sage)
結果
SQL語句僅供參考，有更好的方法歡迎留言和私信！！
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