MySQL 50条必练查询语句

<p>Student(S#,Sname,Sage,Ssex) 学生表</p><p>Course(C#,Cname,T#) 课程表</p><p>SC(S#,C#,score) 成绩表</p><p>Teacher(T#,Tname) 教师表</p><p>问题:</p><p>1、查询“001”课程比“002”课程成绩高的所有学生的学号;</p><p>select a.S# from (select s#,score from SC where C#=’001’) a,(select s#,score</p><p>from SC where C#=’002’) b</p><p>where a.score&gt;b.score and a.s#=b.s#;</p><p>2、查询平均成绩大于60分的同学的学号和平均成绩;</p><p>select S#,avg(score)</p><p>from sc</p><p>group by S# having avg(score) &gt;60;</p><p>3、查询所有同学的学号、姓名、选课数、总成绩;</p><p>select Student.S#,Student.Sname,count(SC.C#),sum(score)</p><p>from Student left Outer join SC on Student.S#=SC.S#</p><p>group by Student.S#,Sname</p><p>4、查询姓“李”的老师的个数;</p><p>select count(distinct(Tname))</p><p>from Teacher</p><p>where Tname like ‘李%’;</p><p>5、查询没学过“叶平”老师课的同学的学号、姓名;</p><p>select Student.S#,Student.Sname</p><p>from Student</p><p>where S# not in (select distinct( SC.S#) from SC,Course,Teacher where SC.C#=Course.C# and Teacher.T#=Course.T# and Teacher.Tname=’叶平’);</p><p>6、查询学过“001”并且也学过编号“002”课程的同学的学号、姓名;</p><p>select Student.S#,Student.Sname from Student,SC where Student.S#=SC.S# and SC.C#=’001’and exists( Select * from SC as SC_2 where SC_2.S#=SC.S# and SC_2.C#=’002’);</p><p>7、查询学过“叶平”老师所教的所有课的同学的学号、姓名;</p><p>select S#,Sname</p><p>from Student</p><p>where S# in (select S# from SC ,Course ,Teacher where SC.C#=Course.C# and Teacher.T#=Course.T# and Teacher.Tname=’叶平’ group by S# having count(SC.C#)=(select count(C#) from Course,Teacher where Teacher.T#=Course.T# and Tname=’叶平’));</p><p>8、查询课程编号“002”的成绩比课程编号“001”课程低的所有同学的学号、姓名;</p><p>Select S#,Sname from (select Student.S#,Student.Sname,score ,(select score from SC SC_2 where SC_2.S#=Student.S# and SC_2.C#=’002’) score2</p><p>from Student,SC where Student.S#=SC.S# and C#=’001’) S_2 where score2</p><p>9、查询所有课程成绩小于60分的同学的学号、姓名;</p><p>select S#,Sname</p><p>from Student</p><p>where S# not in (select Student.S# from Student,SC where S.S#=SC.S# and score&gt;60);</p><p>10、查询没有学全所有课的同学的学号、姓名;</p><p>select Student.S#,Student.Sname</p><p>from Student,SC</p><p>where Student.S#=SC.S# group by Student.S#,Student.Sname having count(C#) &lt;(select count(C#) from Course);</p><p>11、查询至少有一门课与学号为“1001”的同学所学相同的同学的学号和姓名;</p><p>select S#,Sname from Student,SC where Student.S#=SC.S# and C# in select C# from SC where S#=’1001’;</p><p>12、查询至少学过学号为“001”同学所有一门课的其他同学学号和姓名;</p><p>select distinct SC.S#,Sname</p><p>from Student,SC</p><p>where Student.S#=SC.S# and C# in (select C# from SC where S#=’001’);</p><p>13、把“SC”表中“叶平”老师教的课的成绩都更改为此课程的平均成绩;</p><p>update SC set score=(select avg(SC_2.score)</p><p>from SC SC_2</p><p>where SC_2.C#=SC.C# ) from Course,Teacher where Course.C#=SC.C# and Course.T#=Teacher.T# and Teacher.Tname=’叶平’);</p><p>14、查询和“1002”号的同学学习的课程完全相同的其他同学学号和姓名;</p><p>select S# from SC where C# in (select C# from SC where S#=’1002’)</p><p>group by S# having count()=(select count() from SC where S#=’1002’);</p><p>15、删除学习“叶平”老师课的SC表记录;</p><p>Delect SC</p><p>from course ,Teacher</p><p>where Course.C#=SC.C# and Course.T#= Teacher.T# and Tname=’叶平’;</p><p>**16、向SC表中插入一些记录,这些记录要求符合以下条件:没有上过编号“003”课程的同学学号、2、</p><p>号课的平均成绩;**</p><p>Insert SC select S#,’002’,(Select avg(score)</p><p>from SC where C#=’002’) from Student where S# not in (Select S# from SC where C#=’002’);</p><p>17、按平均成绩从高到低显示所有学生的“数据库”、“企业管理”、“英语”三门的课程成绩,按如下形式显示: 学生ID,,数据库,企业管理,英语,有效课程数,有效平均分</p><p>SELECT S# as 学生ID</p><p>,(SELECT score FROM SC WHERE SC.S#=t.S# AND C#=’004’) AS 数据库</p><p>,(SELECT score FROM SC WHERE SC.S#=t.S# AND C#=’001’) AS 企业管理</p><p>,(SELECT score FROM SC WHERE SC.S#=t.S# AND C#=’006’) AS 英语</p><p>,COUNT(*) AS 有效课程数, AVG(t.score) AS 平均成绩</p><p>FROM SC AS t</p><p>GROUP BY S#</p><p>ORDER BY avg(t.score)</p><p>18、查询各科成绩最高和最低的分:以如下形式显示:课程ID,最高分,最低分</p><p>SELECT L.C# As 课程ID,L.score AS 最高分,R.score AS 最低分</p><p>FROM SC L ,SC AS R</p><p>WHERE L.C# = R.C# and</p><p>L.score = (SELECT MAX(IL.score)</p><p>FROM SC AS IL,Student AS IM</p><p>WHERE L.C# = IL.C# and IM.S#=IL.S#</p><p>GROUP BY IL.C#)</p><p>AND</p><p>R.Score = (SELECT MIN(IR.score)</p><p>FROM SC AS IR</p><p>WHERE R.C# = IR.C#</p><p>GROUP BY IR.C#</p><p>);</p><p>19、按各科平均成绩从低到高和及格率的百分数从高到低顺序</p><p>SELECT t.C# AS 课程号,max(course.Cname)AS 课程名,isnull(AVG(score),0) AS 平均成绩</p><p>,100 * SUM(CASE WHEN isnull(score,0)&gt;=60 THEN 1 ELSE 0 END)/COUNT(*) AS 及格百分数</p><p>FROM SC T,Course</p><p>where t.C#=course.C#</p><p>GROUP BY t.C#</p><p>ORDER BY 100 * SUM(CASE WHEN isnull(score,0)&gt;=60 THEN 1 ELSE 0 END)/COUNT(*) DESC</p><p>20、查询如下课程平均成绩和及格率的百分数(用’1行’显示): 企业管理(001),马克思(002),OO&amp;UML (003),数据库(004)</p><p>SELECT SUM(CASE WHEN C# =’001’ THEN score ELSE 0 END)/SUM(CASE C# WHEN ‘001’ THEN 1 ELSE 0 END) AS 企业管理平均分</p><p>,100 * SUM(CASE WHEN C# = ‘001’ AND score &gt;= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN C# = ‘001’ THEN 1 ELSE 0 END) AS 企业管理及格百分数</p><p>,SUM(CASE WHEN C# = ‘002’ THEN score ELSE 0 END)/SUM(CASE C# WHEN ‘002’ THEN 1 ELSE 0 END) AS 马克思平均分</p><p>,100 * SUM(CASE WHEN C# = ‘002’ AND score &gt;= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN C# = ‘002’ THEN 1 ELSE 0 END) AS 马克思及格百分数</p><p>,SUM(CASE WHEN C# = ‘003’ THEN score ELSE 0 END)/SUM(CASE C# WHEN ‘003’ THEN 1 ELSE 0 END) AS UML平均分</p><p>,100 * SUM(CASE WHEN C# = ‘003’ AND score &gt;= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN C# = ‘003’ THEN 1 ELSE 0 END) AS UML及格百分数</p><p>,SUM(CASE WHEN C# = ‘004’ THEN score ELSE 0 END)/SUM(CASE C# WHEN ‘004’ THEN 1 ELSE 0 END) AS 数据库平均分</p><p>,100 * SUM(CASE WHEN C# = ‘004’ AND score &gt;= 60 THEN 1 ELSE 0 END)/SUM(CASE WHEN C# = ‘004’ THEN 1 ELSE 0 END) AS 数据库及格百分数</p><p>FROM SC</p><p>21、查询不同老师所教不同课程平均分从高到低显示</p><p>SELECT max(Z.T#) AS 教师ID,MAX(Z.Tname) AS 教师姓名,C.C# AS 课程ID,MAX(C.Cname) AS 课程名称,AVG(Score) AS 平均成绩</p><p>FROM SC AS T,Course AS C ,Teacher AS Z</p><p>where T.C#=C.C# and C.T#=Z.T#</p><p>GROUP BY C.C#</p><p>ORDER BY AVG(Score) DESC</p><p>**22、查询如下课程成绩第 3 名到第 6 名的学生成绩单:企业管理(001),马克思(002),UML (003),数据库(004)</p><p>[学生ID],[学生姓名],企业管理,马克思,UML,数据库,平均成绩**</p><p>SELECT DISTINCT top 3</p><p>SC.S# As 学生学号,</p><p>Student.Sname AS 学生姓名 ,</p><p>T1.score AS 企业管理,</p><p>T2.score AS 马克思,</p><p>T3.score AS UML,</p><p>T4.score AS 数据库,</p><p>ISNULL(T1.score,0) + ISNULL(T2.score,0) + ISNULL(T3.score,0) + ISNULL(T4.score,0) as 总分</p><p>FROM Student,SC LEFT JOIN SC AS T1</p><p>ON SC.S# = T1.S# AND T1.C# = ‘001’</p><p>LEFT JOIN SC AS T2</p><p>ON SC.S# = T2.S# AND T2.C# = ‘002’</p><p>LEFT JOIN SC AS T3</p><p>ON SC.S# = T3.S# AND T3.C# = ‘003’</p><p>LEFT JOIN SC AS T4</p><p>ON SC.S# = T4.S# AND T4.C# = ‘004’</p><p>WHERE student.S#=SC.S# and</p><p>ISNULL(T1.score,0) + ISNULL(T2.score,0) + ISNULL(T3.score,0) + ISNULL(T4.score,0)</p><p>NOT IN</p><p>(SELECT</p><p>DISTINCT</p><p>TOP 15 WITH TIES</p><p>ISNULL(T1.score,0) + ISNULL(T2.score,0) + ISNULL(T3.score,0) + ISNULL(T4.score,0)</p><p>FROM sc</p><p>LEFT JOIN sc AS T1</p><p>ON sc.S# = T1.S# AND T1.C# = ‘k1’</p><p>LEFT JOIN sc AS T2</p><p>ON sc.S# = T2.S# AND T2.C# = ‘k2’</p><p>LEFT JOIN sc AS T3</p><p>ON sc.S# = T3.S# AND T3.C# = ‘k3’</p><p>LEFT JOIN sc AS T4</p><p>ON sc.S# = T4.S# AND T4.C# = ‘k4’</p><p>ORDER BY ISNULL(T1.score,0) + ISNULL(T2.score,0) + ISNULL(T3.score,0) + ISNULL(T4.score,0) DESC);</p><p>23、统计列印各科成绩,各分数段人数:课程ID,课程名称,[100-85],[85-70],[70-60],[ &lt;60]</p><p>SELECT SC.C# as 课程ID, Cname as 课程名称</p><p>,SUM(CASE WHEN score BETWEEN 85 AND 100 THEN 1 ELSE 0 END) AS [100 - 85]</p><p>,SUM(CASE WHEN score BETWEEN 70 AND 85 THEN 1 ELSE 0 END) AS [85 - 70]</p><p>,SUM(CASE WHEN score BETWEEN 60 AND 70 THEN 1 ELSE 0 END) AS [70 - 60]</p><p>,SUM(CASE WHEN score &lt; 60 THEN 1 ELSE 0 END) AS [60 -]</p><p>FROM SC,Course</p><p>where SC.C#=Course.C#</p><p>GROUP BY SC.C#,Cname;</p><p>24、查询学生平均成绩及其名次</p><p>SELECT 1+(SELECT COUNT( distinct 平均成绩)</p><p>FROM (SELECT S#,AVG(score) AS 平均成绩</p><p>FROM SC</p><p>GROUP BY S#</p><p>) AS T1</p><p>WHERE 平均成绩 &gt; T2.平均成绩) as 名次,</p><p>S# as 学生学号,平均成绩</p><p>FROM (SELECT S#,AVG(score) 平均成绩</p><p>FROM SC</p><p>GROUP BY S#</p><p>) AS T2</p><p>ORDER BY 平均成绩 desc;</p><p>25、查询各科成绩前三名的记录:(不考虑成绩并列情况)</p><p>SELECT t1.S# as 学生ID,t1.C# as 课程ID,Score as 分数</p><p>FROM SC t1</p><p>WHERE score IN (SELECT TOP 3 score</p><p>FROM SC</p><p>WHERE t1.C#= C#</p><p>ORDER BY score DESC</p><p>)</p><p>ORDER BY t1.C#;</p><p>26、查询每门课程被选修的学生数</p><p>select c#,count(S#) from sc group by C#;</p><p>27、查询出只选修了一门课程的全部学生的学号和姓名</p><p>select SC.S#,Student.Sname,count(C#) AS 选课数</p><p>from SC ,Student</p><p>where SC.S#=Student.S# group by SC.S# ,Student.Sname having count(C#)=1;</p><p>28、查询男生、女生人数</p><p>Select count(Ssex) as 男生人数 from Student group by Ssex having Ssex=’男’;</p><p>Select count(Ssex) as 女生人数 from Student group by Ssex having Ssex=’女’;</p><p>29、查询姓“张”的学生名单</p><p>SELECT Sname FROM Student WHERE Sname like ‘张%’;</p><p>30、查询同名同性学生名单,并统计同名人数</p><p>select Sname,count() from Student group by Sname having count()&gt;1;</p><p>31、1981年出生的学生名单(注:Student表中Sage列的类型是datetime)</p><p>select Sname, CONVERT(char (11),DATEPART(year,Sage)) as age</p><p>from student</p><p>where CONVERT(char(11),DATEPART(year,Sage))=’1981’;</p><p>32、查询每门课程的平均成绩,结果按平均成绩升序排列,平均成绩相同时,按课程号降序排列</p><p>Select C#,Avg(score) from SC group by C# order by Avg(score),C# DESC ;</p><p>33、查询平均成绩大于85的所有学生的学号、姓名和平均成绩</p><p>select Sname,SC.S# ,avg(score)</p><p>from Student,SC</p><p>where Student.S#=SC.S# group by SC.S#,Sname having avg(score)&gt;85;</p><p>34、查询课程名称为“数据库”,且分数低于60的学生姓名和分数</p><p>Select Sname,isnull(score,0)</p><p>from Student,SC,Course</p><p>where SC.S#=Student.S# and SC.C#=Course.C# and Course.Cname=’数据库’and score &lt;60;</p><p>35、查询所有学生的选课情况;</p><p>SELECT SC.S#,SC.C#,Sname,Cname</p><p>FROM SC,Student,Course</p><p>where SC.S#=Student.S# and SC.C#=Course.C# ;</p><p>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;</p><p>SELECT distinct student.S#,student.Sname,SC.C#,SC.score</p><p>FROM student,Sc</p><p>WHERE SC.score&gt;=70 AND SC.S#=student.S#;</p><p>37、查询不及格的课程,并按课程号从大到小排列</p><p>select c# from sc where scor e &lt;60 order by C# ;</p><p>38、查询课程编号为003且课程成绩在80分以上的学生的学号和姓名;</p><p>select SC.S#,Student.Sname from SC,Student where SC.S#=Student.S# and Score&gt;80 and C#=’003’;</p><p>39、求选了课程的学生人数</p><p>select count(*) from sc;</p><p>40、查询选修“叶平”老师所授课程的学生中,成绩最高的学生姓名及其成绩</p><p>select Student.Sname,score</p><p>from Student,SC,Course C,Teacher</p><p>where Student.S#=SC.S# and SC.C#=C.C# and C.T#=Teacher.T# and Teacher.Tname=’叶平’ and SC.score=(select max(score)from SC where C#=C.C# );</p><p>41、查询各个课程及相应的选修人数</p><p>select count(*) from sc group by C#;</p><p>42、查询不同课程成绩相同的学生的学号、课程号、学生成绩</p><p>select distinct A.S#,B.score from SC A ,SC B where A.Score=B.Score and A.C# &lt;&gt;B.C# ;</p><p>43、查询每门功成绩最好的前两名</p><p>SELECT t1.S# as 学生ID,t1.C# as 课程ID,Score as 分数</p><p>FROM SC t1</p><p>WHERE score IN (SELECT TOP 2 score</p><p>FROM SC</p><p>WHERE t1.C#= C#</p><p>ORDER BY score DESC</p><p>)</p><p>ORDER BY t1.C#;</p><p>44、统计每门课程的学生选修人数(超过10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,查询结果按人数降序排列,若人数相同,按课程号升序排列</p><p>select C# as 课程号,count(*) as 人数</p><p>from sc</p><p>group by C#</p><p>order by count(*) desc,c#</p><p>45、检索至少选修两门课程的学生学号</p><p>select S#</p><p>from sc</p><p>group by s#</p><p>having count(*) &gt; = 2</p><p>46、查询全部学生都选修的课程的课程号和课程名</p><p>select C#,Cname</p><p>from Course</p><p>where C# in (select c# from sc group by c#)</p><p>47、查询没学过“叶平”老师讲授的任一门课程的学生姓名</p><p>select Sname from Student where S# not in (select S# from Course,Teacher,SC where Course.T#=Teacher.T# and SC.C#=course.C# and Tname=’叶平’);</p><p>48、查询两门以上不及格课程的同学的学号及其平均成绩</p><p>select S#,avg(isnull(score,0)) from SC where S# in (select S# from SC where score &lt;60 group by S# having count(*)&gt;2)group by S#;</p><p>49、检索“004”课程分数小于60,按分数降序排列的同学学号</p><p>select S# from SC where C#=’004’and score &lt;60 order by score desc;</p><p>50、删除“002”同学的“001”课程的成绩</p><p>delete from Sc where S#=’001’and C#=’001’;</p>
RangeTime:0.007039s
RangeMem:219.53 KB
返回顶部 留言