Sql practice
employee表 数据准备
use tempdb go if OBJECT_ID('employee') is not null drop table employee ;with employee(id,name,salary,manager_id) as ( select * from ( values (1,'John',300,3), (2,'Mike',200,3), (3,'Sally',550,4), (4,'Jane',500,7), (5,'Joe',600,7), (6,'Dan',600,3), (7,'Phil',550,NULL) ) as ve(id,name,salary,manager_id) ) select * into employee from employee
--1.Give the names of employees, whose salaries are greater than their immediate managers':
SELECT e.name FROM employee AS e JOIN employee AS m ON e.manager_id = m.id WHERE e.salary > m.salary
--2.What is the average salary of employees without direct reports
--method1 SELECT Avg(e.salary) AS avgsalry FROM employee AS e LEFT JOIN employee AS m ON m.manager_id = e.id WHERE m.id IS NULL --method2 SELECT Avg(e.salary) AS avgsalary FROM employee AS e WHERE NOT EXISTS (SELECT * FROM employee AS m WHERE m.manager_id = e.id)
/******************************************************************************************/
第二题的数据准备:student course courseSelection 三张表
if OBJECT_ID('student','u') is not null drop table student if OBJECT_ID('course','u') is not null drop table course if OBJECT_ID('courseSelection','u') is not null drop table courseSelection ;with student(student_no,student_name) as ( SELECT * FROM (values (1,'John'), (2,'Mike'), (3,'Sally'), (4,'Jane'), (5,'Joe'), (6,'Dan'), (7,'Phil') ) as vstudent(student_no,student_name) ) select * into student from student ;with course (Course_no,Course_name,Course_teacher,Course_credit) as ( SELECT * FROM ( VALUES (1,'Java','Steve',12), (2,'SQLServer','Bill',8), (3,'Windows','Robert',16), (4,'Art','Evan',7), (5,'C#','Steve',9), (6,'HTML','Robert',12), (7,'Finance','Tom',9) ) as vcourse(Course_no,Course_name,Course_teacher,Course_credit) ) select * into course from course ;with CourseSelection(student_no,Course_no,Grade) as ( select * from (values (3,3,57), (3,3,52), (3,3,59), (3,6,57), (3,6,75), (6,2,89), (1,3,93), (1,6,88), (6,7,88), (6,1,99) ) as vcs (student_no,Course_no,Grade) ) select * into CourseSelection from CourseSelection
--1.Find the students name who pass both "Finance" and "SQLServer" and their average grade(pass means "grade" >= 60).
SELECT DISTINCT s.student_name, cs.avggrade FROM student AS s JOIN (SELECT Avg(grade) OVER( partition BY student_no) AS avggrade, * FROM courseselection) AS cs ON s.student_no = cs.student_no JOIN course AS c ON cs.course_no = c.course_no WHERE c.course_name IN ( 'SQLServer', 'Finance' ) AND cs.grade >= 60
--2.Find the students name who failed one course more than 3 times and current still not passed.
--max(grade) <60 and group by course_no having count(*)>=3
SELECT s.student_name FROM student AS s JOIN (SELECT student_no FROM courseselection AS cs GROUP BY student_no, course_no HAVING Count(*) > 2 AND Max(grade) < 60) AS cs ON cs.student_no = s.student_no
--3.Update teacher "Tom" 's grade for everyone, for those grade >= 90, deduct 10, for those grade between 65 and 89, deduct 5, the rest remain.
UPDATE cs SET cs.grade = CASE WHEN cs.grade > 90 THEN cs.grade - 10 WHEN cs.grade BETWEEN 65 AND 89 THEN cs.grade - 5 ELSE cs.grade END FROM course AS c JOIN courseselection AS cs ON c.course_no = cs.course_no WHERE c.course_teacher = 'Tom'
--4.Find the average grade each teacher give to their students, sort the result by descending,
-- if one student attend one course more than once, only take the highest grade into account.
SELECT c.course_teacher, Avg(cs.grade) AS avgGrade FROM course AS c JOIN (SELECT course_no, Max(grade) AS grade FROM courseselection GROUP BY student_no, course_no) AS cs ON c.course_no = cs.course_no GROUP BY c.course_teacher ORDER BY avggrade DESC
--5. Find the student names who is qualify to graduate with following conditions:
--a. Total earn course_credit >= 50
--b. Failed no more than 5 courses
--c. The maximum of course_credit from one teacher is 20.(one teacher may have more than one courses)
SELECT s.student_name FROM student AS s JOIN (SELECT student_no, Sum (CASE WHEN totalcreditfromoneteacher > 20 THEN 20 ELSE totalcreditfromoneteacher END) AS TotalCredit FROM (SELECT student_no, course_teacher, Sum (CASE WHEN cs.grade > 60 THEN c.course_credit ELSE 0 END) AS TotalCreditFromOneTeacher FROM course AS c JOIN courseselection AS cs ON cs.course_no = c.course_no GROUP BY student_no, course_teacher) AS A GROUP BY student_no) AS cs ON cs.student_no = s.student_no JOIN (SELECT DISTINCT student_no FROM courseselection cs GROUP BY student_no, course_no HAVING Count(DISTINCT course_no) < 5) AS stuentfaillessthan5courses ON s.student_no = stuentfaillessthan5courses.student_no WHERE cs.TotalCredit>50
Sql practice的更多相关文章
- Sql Practice 2
之前写了一个SP用来向dimention table插入0 -1 dummy row的值,但今天在process adventureworksdw2008示例 数据库的时候报错,查看了一下,是因为自己 ...
- 历经15个小时,终于评出这8本最受欢迎的SQL书籍
文章发布于公号[数智物语] (ID:decision_engine),关注公号不错过每一篇干货. 来源 | 程序员书库(ID:OpenSourceTop) 原文链接 | https://www.lif ...
- Atitit 数据存储视图的最佳实际best practice attilax总结
Atitit 数据存储视图的最佳实际best practice attilax总结 1.1. 视图优点:可读性的提升1 1.2. 结论 本着可读性优先于性能的原则,面向人类编程优先于面向机器编程,应 ...
- The Practice of .NET Cross-Platforms
0x01 Preface This post is mainly to share the technologies on my practice about the .NET Cross-Platf ...
- 谈一谈SQL Server中的执行计划缓存(上)
简介 我们平时所写的SQL语句本质只是获取数据的逻辑,而不是获取数据的物理路径.当我们写的SQL语句传到SQL Server的时候,查询分析器会将语句依次进行解析(Parse).绑定(Bind).查询 ...
- Partitioning & Archiving tables in SQL Server (Part 1: The basics)
Reference: http://blogs.msdn.com/b/felixmar/archive/2011/02/14/partitioning-amp-archiving-tables-in- ...
- 可输出sql的PrepareStatement封装
import java.io.InputStream; import java.io.Reader; import java.net.URL; import java.sql.Connection; ...
- sql是如何执行一个查询的!
引用自:http://rusanu.com/2013/08/01/understanding-how-sql-server-executes-a-query/ Understanding how SQ ...
- C#读写SQL Server数据库图片
效果图: 下载链接: http://download.csdn.net/detail/u010312811/9492402 1.创建一个Winform窗体,窗体分为“数据上传”和“数据读取”两部分: ...
随机推荐
- 重新想象 Windows 8 Store Apps (53) - 绑定: 与 ObservableCollection CollectionViewSource VirtualizedFilesVector VirtualizedItemsVector 绑定
[源码下载] 重新想象 Windows 8 Store Apps (53) - 绑定: 与 ObservableCollection CollectionViewSource VirtualizedF ...
- Access-Control-Allow-Origin: Dealing with CORS Errors in Angular
https://daveceddia.com/access-control-allow-origin-cors-errors-in-angular/ Getting this error in you ...
- FreeBSD暂时用9.X系列为宜
今天尝试在FreeBSD10 上编译c代码,发现gcc被换成llvm后,环境配置需要重新学习.
- ACdream 1214---矩阵连乘
ACdream 1214---矩阵连乘 Problem Description You might have noticed that there is the new fashion among r ...
- python3学习笔记目录
目录: Python基础(一),Day1 python基础(二),Day2 python函数和常用模块(一),Day3 python函数和常用模块(二),Day4 python函数和常用模块(三),D ...
- If you insist running as root, then set the environment variable RUN_AS_USER=root...
版权声明:本文为博主原创文章,不经博主允许注明链接即可转载. If you insist running as root, then set theenvironment variable RUN_A ...
- 如何选择RabbitMQ的消息保存方式?
RabbitMQ对于queue中的message的保存方式有两种方式:disc和ram.如果采用disc,则需要对exchange/queue/delivery mode都要设置成durable模式. ...
- 安全协议:SSL、TSL、SSH概述
SSL(Secure Socket Layer--安全套接字层):为网络通信安全以及数据完整性提供保障的一种安全协议,在TCP/IP的传输层对网络连接进行加密: TSL(Transport Layer ...
- [js开源组件开发]js文本框计数组件
js文本框计数组件 先上效果图: 样式可以自行调整 ,它的功能提供文本框的实时计数,并作出对应的操作,比如现在超出了,点击下面的按钮后,文本框会闪动两下,阻止提交.具体例子可以点击demo:http: ...
- css清除浮动定位造成的异常
清除浮动是为了解决高度塌陷的问题:内层有好几个div有宽有高,并且选择了浮动定位,但是外层的div却并没有设置宽高.在非IE浏览器(如Firefox)下,当容器的高度为auto,且容器的内容中有浮动( ...