最全50個Mysql數(shù)據(jù)庫查詢練習題
此數(shù)據(jù)庫查詢語句是網(wǎng)絡(luò)上50個數(shù)據(jù)庫查詢練習題目，網(wǎng)上有些版本是oracle語句寫的，大多數(shù)公司還是用免費的mysql數(shù)據(jù)庫，以下都是mysql版本，全部都有驗證過。
表名和字段
–1.學生表
Student(s#, sname, sage,ssex) –學生編號,學生姓名, 出生年月,學生性別
–2.課程表
Course(c#,cname,t#) – –課程編號, 課程名稱, 教師編號
–3.教師表
Teacher(t#,tname) –教師編號,教師姓名
–4.成績表
Sc(s#,c#,score) –學生編號,課程編號,分數(shù)
測試數(shù)據(jù)
用數(shù)據(jù)庫可視化工具做練習非常方便，推薦使用sqlyog，軟件圖標是一只海豚。
在新連接種填上本機地址，用戶名，密碼和端口就直接連上mysql。
所有測試數(shù)據(jù)如下：
# --插入學生表測試數(shù)據(jù)
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' , '李云' , '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');
# --插入課程表測試數(shù)據(jù)
INSERT INTO course VALUES('01' , '語文' , '02');
INSERT INTO course VALUES('02' , '數(shù)學' , '01');
INSERT INTO course VALUES('03' , '英語' , '03');
# --插入教師表測試數(shù)據(jù)
INSERT INTO teacher VALUES('01' , '張三');
INSERT INTO teacher VALUES('02' , '李四');
INSERT INTO teacher VALUES('03' , '王五');
# --插入成績表測試數(shù)據(jù)
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);
最后是50個數(shù)據(jù)庫查詢練習，已經(jīng)驗證過，是mysql版本的。
1. 查詢" 01 "課程比" 02 "課程成績高的學生的信息及課程分數(shù)
SELECT * FROM
(SELECT `s#` AS sno1, `c#`AS cno1, score FROM sc WHERE `c#`=01) a
LEFT JOIN
(SELECT `s#` AS sno2, `c#`AS cno2, score FROM sc WHERE `c#`=02) b
ON a.sno1 = b.sno2
WHERE a.score > b.score
1.1 查詢同時存在" 01 "課程和" 02 "課程的情況
SELECT * FROM
(SELECT `s#` AS sno1, `c#`AS cno1, score FROM sc WHERE `c#`=01) a
LEFT JOIN
(SELECT `s#` AS sno2, `c#`AS cno2, score FROM sc WHERE `c#`=02) b
ON a.sno1 = b.sno2
WHERE sno2 IS NOT NULL
1.2 查詢存在" 01 "課程但可能不存在" 02 "課程的情況(不存在時顯示為 null )
SELECT * FROM
(SELECT `s#` AS sno1, `c#`AS cno1, score FROM sc WHERE `c#`=01) a
LEFT JOIN
(SELECT `s#` AS sno2, `c#`AS cno2, score FROM sc WHERE `c#`=02) b
ON a.sno1 = b.sno2
1.3 查詢不存在" 01 "課程但存在" 02 "課程的情況
SELECT * FROM
sc WHERE `c#`='02' AND `s#` NOT IN (SELECT `s#` FROM sc WHERE `c#`='01')
2. 查詢平均成績大于等于 60 分的同學的學生編號和學生姓名和平均成績
SELECT a.`s#`,b.`sname`, a.avg_score FROM
(SELECT `s#` ,AVG(score) AS avg_score FROM sc GROUP BY `s#`) AS a
LEFT JOIN student AS b
ON a.`s#` = b.`s#`
WHERE a.avg_score >=60
3. 查詢在 SC 表存在成績的學生信息
SELECT * FROM student WHERE `s#` IN (SELECT DISTINCT `s#` FROM sc)
4. 查詢所有同學的學生編號、學生姓名、選課總數(shù)、所有課程的總成績(沒成績的顯示為 NULL )
SELECT `s#` ,sname , course_num , score_sum FROM
(SELECT `s#`, sname FROM student ) AS a
LEFT JOIN
(SELECT `s#` AS sno ,COUNT(`c#`) AS course_num ,SUM(score) AS score_sum FROM sc GROUP BY sno) AS b
ON a.`s#` = b.sno
4.1 查有成績的學生信息
# 在最外面一層select的時候，不可以用函數(shù)
# 如果兩張表連接之后，有相同的字段，這時候select就需要把其中一個字段改名
SELECT `s#` ,sname , course_num , score_sum FROM
(SELECT `s#`, sname FROM student ) AS a
LEFT JOIN
(SELECT `s#` AS sno ,COUNT(`c#`) AS course_num ,SUM(score) AS score_sum FROM sc GROUP BY sno) AS b
ON a.`s#` = b.sno
WHERE course_num IS NOT NULL
5. 查詢「李」姓老師的數(shù)量
SELECT COUNT(*) FROM teacher WHERE tname LIKE '李%'
6. 查詢學過「張三」老師授課的同學的信息
# 張三老師是01號
SELECT * FROM student WHERE `s#` IN
(SELECT `s#` FROM sc WHERE `c#` =
(SELECT `c#` FROM course WHERE `t#` =
(SELECT `t#` FROM teacher WHERE tname='張三')))
# 7. 查詢沒有學全所有課程的同學的信息
SELECT `s#`,COUNT(`c#`) AS course_num FROM sc GROUP BY `s#`
HAVING course_num < (SELECT COUNT(*) FROM course)
# 8. 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
SELECT * FROM student WHERE `s#` IN
(SELECT DISTINCT `s#` FROM sc WHERE `c#` IN
(SELECT `c#` FROM sc WHERE `s#`=01))
AND `s#`!= 01
# 9. 查詢和"01"號的同學學習的課程完全相同的其他同學的信息
SELECT `s#` FROM
(SELECT * FROM sc
LEFT JOIN
(SELECT `c#` AS cno FROM sc WHERE `s#` =01) a
ON sc.`c#` = a.cno) AS b
GROUP BY `s#`
HAVING COUNT(b.`s#`) = (SELECT COUNT(`c#`) AS cno FROM sc WHERE `s#` =01)
# 10. 查詢沒學過"張三"老師講授的任一門課程的學生姓名
# 張三是01
# 01老師是教數(shù)學，c#是02
SELECT * FROM student WHERE `s#` NOT IN
(SELECT DISTINCT `s#` FROM sc WHERE `c#` IN
(SELECT `c#` FROM course WHERE `t#` IN
(SELECT `t#` FROM teacher WHERE tname = '張三')))
# 11. 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 `s#`, sname, avg_score FROM
(SELECT `s#`, sname FROM student WHERE `s#` IN
(SELECT a.`s#` FROM
(SELECT `s#`,COUNT(`c#`) AS num FROM sc WHERE score <60 GROUP BY `s#`) a
WHERE num >=2)) AS b
LEFT JOIN
(SELECT `s#` AS sno ,AVG(score) AS avg_score FROM sc GROUP BY `s#`) AS c
ON b.`s#` = c.sno
# 12. 檢索" 01 "課程分數(shù)小于 60，按分數(shù)降序排列的學生信息
SELECT `s#`, sname, score FROM
student AS a
LEFT JOIN
(SELECT `s#` AS sno,`c#`,score FROM sc WHERE `c#`= 01 AND score <60 )b
ON a.`s#`= b.sno
WHERE score IS NOT NULL
ORDER BY score DESC
# 13. 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 `s#` ,AVG(score) AS avg_score FROM sc GROUP BY `s#` ORDER BY avg_score DESC
# 14. 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(yōu)良率，優(yōu)秀率
# 及格為>=60，中等為：70-80，優(yōu)良為：80-90，優(yōu)秀為：>=90
# 要求輸出課程號和選修人數(shù)，查詢結(jié)果按人數(shù)降序排列，若人數(shù)相同，按課程號升序排列
SELECT DISTINCT a.`c#`,cname,最高分,最低分,平均分,及格率,中等率,優(yōu)良率,優(yōu)秀率 FROM sc a LEFT JOIN course ON a.`c#`=course.`c#` LEFT JOIN (SELECT `c#`, MAX(score)最高分, MIN(score)最低分, AVG(score)平均分 FROM sc GROUP BY `c#`)b ON a.`c#`=b.`c#` LEFT JOIN (SELECT `c#`, ROUND( r1 /cnt * 100, 2 ) AS 及格率 FROM (SELECT `c#`, (SUM(CASE WHEN score >=60 THEN 1 ELSE 0 END)*1.00) AS r1 , COUNT(*) AS cnt FROM sc GROUP BY `c#`) c1) c ON a.`c#`=c.`c#` LEFT JOIN (SELECT `c#`, ROUND( r2 /cnt * 100, 2 ) AS 中等率 FROM (SELECT `c#`, (SUM(CASE WHEN score >=70 AND score<80 THEN 1 ELSE 0 END)*1.00) AS r2 , COUNT(*) AS cnt FROM sc GROUP BY `c#`) d1) d ON a.`c#`=d.`c#` LEFT JOIN (SELECT `c#`, ROUND( r3 /cnt * 100, 2 ) AS 優(yōu)良率 FROM (SELECT `c#`, (SUM(CASE WHEN score >=80 AND score<90 THEN 1 ELSE 0 END)*1.00) AS r3 , COUNT(*) AS cnt FROM sc GROUP BY `c#`) e1) e ON a.`c#`=e.`c#` LEFT JOIN (SELECT `c#`, ROUND( r4 /cnt * 100, 2 ) AS 優(yōu)秀率 FROM (SELECT `c#`, (SUM(CASE WHEN score >=90 THEN 1 ELSE 0 END)*1.00) AS r4 , COUNT(*) AS cnt FROM sc GROUP BY `c#`) f1) f ON a.`c#`=f.`c#`
# 15. 按各科成績進行排序，并顯示排名， Score 重復時保留名次空缺
# mysql中沒有rank()函數(shù) # 這種是重復時候保留名次，所以最后名次和人數(shù)是一樣的 SELECT `s#`, `c#`, score, rank FROM (SELECT `s#`, `c#`, score, @currank := IF(@prevrank = score, @currank, @incrank) AS rank, @incrank := @incrank + 1, @prevrank := score FROM sc , ( SELECT @currank :=0, @prevrank := NULL, @incrank := 1 ) r ORDER BY score DESC) s
# 15.1 按各科成績進行排序，并顯示排名， Score 重復時合并名次
# 這種是當有重復名次的時候變成只有一個名次，所以排名的數(shù)量會變少 SELECT `s#`, `c#`, score, CASE WHEN @prevrank = score THEN @currank WHEN @prevrank := score THEN @currank := @currank + 1 END AS rank FROM sc, (SELECT @currank :=0, @prevrank := NULL) r ORDER BY score DESC
# 16. 查詢學生的總成績，并進行排名，總分重復時保留名次空缺
# from后面不需要加表的別名 SELECT `s#`, sum_score, rank FROM (SELECT `s#`, sum_score, @currank := IF(@prevrank = sum_score, @currank, @incrank) AS rank, @incrank := @incrank + 1, @prevrank := sum_score FROM (SELECT `s#`, SUM(score) AS sum_score FROM sc GROUP BY `s#`) c , (SELECT @currank :=0, @prevrank := NULL, @incrank := 1) r ORDER BY sum_score DESC) s
# 16.1 查詢學生的總成績，并進行排名，總分重復時不保留名次空缺
SELECT c.*, CASE WHEN @prevrank = c.sum_score THEN @currank WHEN @prevrank := c.sum_score THEN @currank := @currank + 1 END AS rank FROM (SELECT a.`s#`,a.sname,SUM(score) AS sum_score FROM (student AS a RIGHT JOIN sc AS b ON a.`s#` = b.`s#`) GROUP BY a.`s#` ) c , (SELECT @currank := 0 , @prevrank :=NULL ) d ORDER BY sum_score DESC
# 17. 統(tǒng)計各科成績各分數(shù)段人數(shù)：課程編號，課程名稱，[100-85]，[85-70]，[70-60]，[60-0] 及所占百分比
SELECT a.`c#` , b.cname,
SUM(CASE WHEN score >=85 AND score <=100 THEN 1 ELSE 0 END ) '[100-85]',
SUM(CASE WHEN score >=85 AND score <=100 THEN 1 ELSE 0 END )*1.00/COUNT(*) AS '[100-85]percent',
SUM(CASE WHEN score < 85 AND score >= 70 THEN 1 ELSE 0 END ) '(85-70]',
SUM(CASE WHEN score < 85 AND score >= 70 THEN 1 ELSE 0 END )*1.00/COUNT(*) AS '(85-70]percent',
SUM(CASE WHEN score < 70 AND score >= 60 THEN 1 ELSE 0 END ) '(70-60]',
SUM(CASE WHEN score < 70 AND score >= 60 THEN 1 ELSE 0 END )*1.00/COUNT(*) AS '(85-70]percent',
SUM(CASE WHEN score < 60 AND score >= 0 THEN 1 ELSE 0 END ) '(60-0]',
SUM(CASE WHEN score < 60 AND score >= 0 THEN 1 ELSE 0 END )*1.00/COUNT(*) AS '(85-70]percent',
COUNT(*) AS counts
FROM sc a LEFT JOIN course b ON a.`c#` = b.`c#`
GROUP BY `c#`
# 18. 查詢各科成績前三名的記錄
SELECT * FROM sc a WHERE (SELECT COUNT(*) FROM sc WHERE `c#`=a.`c#` AND score>a.score)<3 ORDER BY a.`c#`, a.score DESC;
# 19. 查詢每門課程被選修的學生數(shù)
SELECT `c#`, COUNT(`s#`) FROM (SELECT `s#`,`c#` FROM sc ORDER BY `c#`)a GROUP BY `c#` SELECT a.`c#` , b.cname ,COUNT(*) AS num FROM sc a LEFT JOIN course b ON a.`c#` = b.`c#` GROUP BY a.`c#`;
# 20. 查詢出只選修兩門課程的學生學號和姓名
SELECT a.`s#`, a.sname ,cnt FROM student a LEFT JOIN (SELECT `s#`,COUNT(`c#`) AS cnt FROM sc GROUP BY `s#`) b ON a.`s#`=b.`s#` WHERE cnt=2
# 21. 查詢男生、女生人數(shù)
SELECT ssex,COUNT(ssex) FROM student GROUP BY ssex
# 22. 查詢名字中含有「風」字的學生信息
SELECT * FROM student WHERE sname LIKE '%風%'
# 23. 查詢同名同性學生名單，并統(tǒng)計同名人數(shù)
SELECT a.*,b.同名人數(shù) FROM student a LEFT JOIN (SELECT sname,ssex,COUNT(*) AS 同名人數(shù) FROM student GROUP BY sname,ssex)b ON a.sname=b.sname AND a.ssex=b.ssex WHERE b.同名人數(shù)>1
# 24. 查詢 1990 年出生的學生名單
SELECT * FROM student WHERE YEAR(sage) = 1990
# 25. 查詢每門課程的平均成績，結(jié)果按平均成績降序排列，平均成績相同時，按課程編號升序排列
SELECT `c#`, ROUND(AVG(score),2) AS avg_score FROM sc GROUP BY `c#` ORDER BY `c#` ASC
# 26. 查詢平均成績大于等于 85 的所有學生的學號、姓名和平均成績
SELECT c.`s#`,sname ,avg_score FROM (student c LEFT JOIN (SELECT `s#`, avg_score FROM (SELECT `s#` ,ROUND(AVG(score),2) AS avg_score FROM sc GROUP BY `s#` ORDER BY avg_score DESC)a WHERE avg_score >=85) b ON c.`s#` =b.`s#`) WHERE avg_score IS NOT NULL
# 27. 查詢課程名稱為「數(shù)學」，且分數(shù)低于 60 的學生姓名和分數(shù)
SELECT a.`s#`,a.sname,b.math, b.score FROM student a LEFT JOIN (SELECT `s#`,`c#` AS math ,score FROM sc WHERE `c#` IN (SELECT `c#` FROM course WHERE cname = '數(shù)學') AND sc.score <60) b ON a.`s#`=b.`s#` WHERE b.score IS NOT NULL
# 28. 查詢所有學生的課程及分數(shù)情況（存在學生沒成績，沒選課的情況）
SELECT a.`s#`,a.`sname`,a.`sage`,a.`ssex`,b.`c#`,b.score FROM student a LEFT JOIN sc b ON a.`s#` = b.`s#` LEFT JOIN course c ON c.`c#` = b.`c#`
# 29. 查詢?nèi)魏我婚T課程成績在 70 分以上的姓名、課程名稱和分數(shù)
SELECT a.`s#`,a.`sname`,a.`sage`,a.`ssex`,b.`c#`,b.score FROM student a LEFT JOIN (SELECT `s#`,`c#`,score FROM sc WHERE score >70) b ON a.`s#`=b.`s#` LEFT JOIN course c ON c.`c#`=b.`c#` WHERE score IS NOT NULL
# 30. 查詢不及格的課程
SELECT * FROM sc WHERE score < 60
# 31. 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 a.`s#`, a.sname ,b.score FROM
student a
LEFT JOIN
(SELECT * FROM sc WHERE `c#`='01' AND score >= 80) b
ON a.`s#` = b.`s#`
WHERE score IS NOT NULL
# 32. 求每門課程的學生人數(shù)
SELECT `c#`,COUNT(`c#`) FROM sc GROUP BY `c#`
# 33. 成績不重復，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
SELECT a.`s#`, a.`sname` ,b.`c#`, b.max_score FROM
student a
LEFT JOIN
(SELECT `s#` AS sid,`c#` ,MAX(score) AS max_score FROM sc WHERE `c#` IN
(SELECT `c#` FROM course WHERE `t#` IN
(SELECT `t#` FROM teacher WHERE tname = '張三'))) b
ON a.`s#`=b.sid
WHERE max_score IS NOT NULL
# 34. 成績有重復的情況下，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
SELECT * FROM (SELECT dd.*, CASE WHEN @prevrank = dd.score THEN @currank WHEN @prevrank := dd.score THEN @currank := @currank + 1 END AS rank FROM (SELECT a.*,b.score FROM student a LEFT JOIN sc b ON a.`s#` = b.`s#` LEFT JOIN course c ON b.`c#` = c.`c#` LEFT JOIN teacher d ON c.`t#` = d.`t#` WHERE d.tname = '張三' ) dd,(SELECT @currank := 0 , @prevrank :=NULL ) ff ORDER BY score DESC) AS dddddddd WHERE rank = 1;
# 35. 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 DISTINCT a.`s#`, a.`c#`, a.score FROM sc AS a JOIN sc AS b WHERE a.`c#` != b.`c#` AND a.score = b.score AND a.`s#` != b.`s#` ORDER BY a.`s#`, a.`c#`, a.score
# 36. 查詢每門功課成績最好的前兩名
# 此題和18題相同 SELECT * FROM sc a WHERE (SELECT COUNT(*) FROM sc WHERE `c#`=a.`c#` AND score>a.score)<2 ORDER BY a.`c#`, a.score DESC;
# 37. 統(tǒng)計每門課程的學生選修人數(shù)（超過 5 人的課程才統(tǒng)計）
# 要求輸出課程號和選修人數(shù)，查詢結(jié)果按人數(shù)降序排列，若人數(shù)相同，按課程號升序排列 SELECT a.`c#`, COUNT(*) AS num FROM course a LEFT JOIN sc b ON a.`c#` = b.`c#` GROUP BY a.`c#` HAVING num > 5 ORDER BY num,a.`c#`
# 38. 檢索至少選修兩門課程的學生學號
SELECT DISTINCT`s#`,COUNT(`c#`) AS num FROM sc GROUP BY `s#` HAVING num >=2
# 39. 查詢選修了全部課程的學生信息
SELECT * FROM (SELECT `s#`,COUNT(*) AS num FROM sc GROUP BY `s#` ) b WHERE num = (SELECT COUNT(*) FROM course)
# 40. 查詢各學生的年齡，只按年份來算
SELECT *, YEAR(NOW()) - YEAR(sage) AS age FROM student
# 41. 查詢本周過生日的學生
SELECT * FROM
(SELECT * , WEEK(sage), MONTH(sage),DAY(sage),
WEEK(STR_TO_DATE(CONCAT_WS(',',YEAR(NOW()),MONTH(sage),DAY(sage)),'%y,%m,%d')) AS w FROM student) a
WHERE w = WEEK(NOW())
# 42. 查詢下周過生日的學生
SELECT * FROM
(SELECT * , WEEK(sage), MONTH(sage),DAY(sage),WEEK(NOW()),
WEEK(STR_TO_DATE(CONCAT_WS(',',YEAR(NOW()),MONTH(sage),DAY(sage)),'%y,%m,%d')) AS w FROM student) a
WHERE w + 2 = WEEK(NOW())
# 43. 查詢本月過生日的學生
SELECT * , MONTH(sage),MONTH(NOW()) FROM student WHERE MONTH(sage) = MONTH(NOW())
# 44. 查詢下月過生日的學生
SELECT * , MONTH(sage),MONTH(NOW()) FROM student WHERE MONTH(sage) = MONTH(NOW()) + 1
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