SQL学习笔记（1）

SQL语言——SELECT查询操作 实验四

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前言

初学SQL数据库，做了一些简单的SQL语句相关实验，作为学习进度更近，方便后期复习

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以下是本篇文章正文内容，下面案例可供参考

一、实验学习目的

表或视图数据的各种查询(与统计)SQL命令操作，具体分为:
1、了解查询的概念和方法。
2、掌握SQLServer集成管理器查询子窗口中执行SELECT操作的方法。
3、掌握SELECT语句在单表查询中的应用。
4、掌握SELECT语句在多表查询中的应用。
5、掌握SELECT语句在复杂查询中的使用方法。

二、实验内容

1. 检索王同学不学的课程的课程号。

SELECT DISTINCT Sname
FROM Student
WHERE Ssex='女' and EXISTS(SELECT *
                           FROM SC
                           WHERE Sno=Student.Sno) 

2. 检索王同学不学的课程的课程号

SELECT Cno
FROM Course
WHERE CNO NOT IN (SELECT CNO
                  FROM SC,STUDENT
          WHERE STUDENT.SNO = SC.SNO AND STUDENT.SNAME LIKE '王%')

3.检索全部学生都选修的课程的课程号与课程名

SELECT CNO,Cname
FROM COURSE
WHERE NOT EXISTS(SELECT *
                 FROM Student
                 WHERE NOT EXISTS(SELECT *
                                  FROM SC
                WHERE SC.Sno = Student.Sno AND SC.Cno = COURSE.Cno))

4.检索选修了所有3学分课程的学生学号

SELECT SNO
FROM SC
WHERE CNO IN(SELECT CNO
             FROM COURSE
             WHERE CCREDIT = 3)
             GROUP BY SNO
             HAVING COUNT (CNO) = (SELECT COUNT(*)
                                   FROM COURSE
                                   WHERE CCREDIT =3)

5.统计所有（每个）学生选修的课程门数，要求显示学号和课程门数，包括没有选课的学生

SELECT STUDENT.SNO,COUNT (DISTINCT CNO)
FROM STUDENT LEFT OUTER JOIN SC ON STUDENT.SNO =SC.SNO
GROUP BY STUDENT.SNO

6.求选修课程号为4课程的学生的平均年龄。

SELECT AVG(Sage)
FROM Student
WHERE SNO IN (SELECT SNO
              FROM SC
              WHERE Cno = 4)

7.求学分为3的每门课程的学生平均成绩

SELECT cno,AVG(GRADE)
FROM SC
WHERE cno in (select cno
              from course
              where ccredit = 3)
GROUP BY cno

8.检索学号比王非同学大，而年龄比他小的学生姓名

SELECT Sname
FROM Student
WHERE Sage <(SELECT Sage
             FROM Student
             WHERE Sname = '王非') AND Sno > (SELECT Sno
                                              FROM Student
                                              WHERE Sname = '王非')

9.求年龄大于女同学平均年龄的男学生姓名和年龄

SELECT Sname,Sage
FROM STUDENT
WHERE Sage > (SELECT AVG(SAGE)
              FROM Student
              WHERE Ssex = '女') AND Ssex = '男'

10.求年龄大于所有女同学年龄的男学生姓名和年龄

SELECT Sname,Sage
FROM Student
WHERE Sage >(SELECT MAX(SAGE)
             FROM Student
             WHERE Ssex = '女')  AND Ssex = '男'

11.检索所有比“王华”年龄大的学生姓名、年龄和性别。

SELECT SNAME,SAGE,SSEX
FROM STUDENT
WHERE Sage > (SELECT SAGE
              FROM Student
              WHERE SNAME = '王华')

12.检索选修4门以上课程的学生总成绩(不统计不及格的课程)，并要求按总成绩的降序排列出来

SELECT SNO,SUM(GRADE)
FROM SC
WHERE SNO IN(SELECT SNO
             FROM SC
             GROUP BY SNO
	         HAVING COUNT(*)>4) AND GRADE>=60
GROUP BY SNO
ORDER BY SUM(GRADE) DESC

13. 查询选修’8105’课程的成绩高于’980302’号同学成绩的所有同学的记录（学号和成绩）

SELECT SNO,GRADE
FROM SC
WHERE CNO = '8105' AND GRADE >(SELECT GRADE 
                               FROM SC
                               WHERE SNO = '980302' AND CNO = '8105')

总结

以上就是这次实验的内容，本次只做了些最基本的实验，没有很大的难度，希望期末能过