SQL 基础面试题01☆☆☆_分组统计等怎么加虚拟列1班和2班相差的分数怎么用sql计算

Posted 2021-11-04 平凡加班狗

SQL 基础面试题01☆☆☆系列文章目录

文章目录

• SQL 基础面试题01☆☆☆系列文章目录
• 表结构
• 1、将这3科弄成如下模式：
• 2、2班总分比1班总分高出多少的报表
• • 分析，怎么加虚拟列
  • 分析：1班和2班相差的分数怎么用sql计算
• 3、附：完整sql代码

表结构

CREATE TABLE [dbo].[AScore](
	[Name] [nvarchar](50) NULL,
	[SubjectName] [nvarchar](50) NULL,
	[Score] [decimal](18, 2) NULL,
	[ClassNo] [nvarchar](50) NULL
) ON [PRIMARY]
GO
CREATE TABLE [dbo].[AScoreZone](
	[ClassNo] [nvarchar](50) NULL,
	[ClassName] [nvarchar](50) NULL,
	[CityZone] [nvarchar](50) NULL
) ON [PRIMARY]
GO
INSERT [dbo].[AScoreZone] ([ClassNo], [ClassName], [CityZone]) VALUES (N'1', N'一班', N'福田区')
INSERT [dbo].[AScoreZone] ([ClassNo], [ClassName], [CityZone]) VALUES (N'2', N'二班', N'福田区')
/****** Object:  Table [dbo].[AScore]    Script Date: 09/01/2017 21:22:23 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
INSERT [dbo].[AScore] ([Name], [SubjectName], [Score], [ClassNo]) VALUES (N'刘峰', N'语文', CAST(90.00 AS Decimal(18, 2)), N'1')
INSERT [dbo].[AScore] ([Name], [SubjectName], [Score], [ClassNo]) VALUES (N'刘峰', N'数学', CAST(80.00 AS Decimal(18, 2)), N'1')
INSERT [dbo].[AScore] ([Name], [SubjectName], [Score], [ClassNo]) VALUES (N'刘峰', N'英语', CAST(80.11 AS Decimal(18, 2)), N'1')
INSERT [dbo].[AScore] ([Name], [SubjectName], [Score], [ClassNo]) VALUES (N'刘丹', N'语文', CAST(80.00 AS Decimal(18, 2)), N'2')
INSERT [dbo].[AScore] ([Name], [SubjectName], [Score], [ClassNo]) VALUES (N'刘丹', N'数学', CAST(98.00 AS Decimal(18, 2)), N'2')
INSERT [dbo].[AScore] ([Name], [SubjectName], [Score], [ClassNo]) VALUES (N'刘晶', N'英语', CAST(90.00 AS Decimal(18, 2)), N'2')
INSERT [dbo].[AScore] ([Name], [SubjectName], [Score], [ClassNo]) VALUES (N'刘晶', N'语文', CAST(90.00 AS Decimal(18, 2)), N'2')
INSERT [dbo].[AScore] ([Name], [SubjectName], [Score], [ClassNo]) VALUES (N'小浩', N'语文', CAST(100.00 AS Decimal(18, 2)), N'3')
INSERT [dbo].[AScore] ([Name], [SubjectName], [Score], [ClassNo]) VALUES (N'小浩', N'英语', CAST(89.00 AS Decimal(18, 2)), N'3')
INSERT [dbo].[AScore] ([Name], [SubjectName], [Score], [ClassNo]) VALUES (N'小浩', N'数学', CAST(11.00 AS Decimal(18, 2)), N'3')

1、将这3科弄成如下模式：

	语文	数学	英语
刘晶	X	X	X
刘丹	X	X	X
刘峰	X	X	X

答：

select Name,
	   SUM(case subjectName when '语文' then Score else 0 end) 语文,
	   SUM(case subjectName when '数学' then Score else 0 end) 数学, 
	   SUM(case subjectName when '英语' then Score else 0 end) 英语 
	   from AScore group by Name 

2、2班总分比1班总分高出多少的报表

区	班	班	高出分数
福田	1班	2班	50分

答
分析

分析，怎么加虚拟列

分析：1班和2班相差的分数怎么用sql计算

所以我们也可以这样写

分析完 下面就可以正式开始写完整的sql了
最终答案

select CityZone 区,'1班' 班,'2班' 班,(select 
((select sum(Score)二班总分 from AScore,AScoreZone where AScore.ClassNo=AScoreZone.ClassNo and ClassName='二班'group by ClassName)-
(select sum(Score)一班总分 from AScore,AScoreZone where AScore.ClassNo=AScoreZone.ClassNo and ClassName='一班'group by ClassName))
)'高出分数' from AScore,AScoreZone where AScore.ClassNo=AScoreZone.ClassNo group by CityZone

3、附：完整sql代码

select * from AScore 
--第1题
select Name,
	   SUM(case subjectName when '语文' then Score else 0 end) 语文,
	   SUM(case subjectName when '数学' then Score else 0 end) 数学, 
	   SUM(case subjectName when '英语' then Score else 0 end) 英语 
	   from AScore group by Name 
	   
--第2题
select * from AScore
select * from AScoreZone

select * from AScore,AScoreZone where AScore.ClassNo=AScoreZone.ClassNo


select CityZone 区,'1班' 班,'2班' 班 from AScore,AScoreZone where AScore.ClassNo=AScoreZone.ClassNo group by CityZone


-- 1班和2班相差的分数
select ClassName,sum(Score)总分 from AScore,AScoreZone where AScore.ClassNo=AScoreZone.ClassNo group by ClassName

select 
((select sum(Score)二班总分 from AScore,AScoreZone where AScore.ClassNo=AScoreZone.ClassNo and ClassName='二班'group by ClassName)-
(select sum(Score)一班总分 from AScore,AScoreZone where AScore.ClassNo=AScoreZone.ClassNo and ClassName='一班'group by ClassName))'高出分数'


select CityZone 区,'1班' 班,'2班' 班,(select 
((select sum(Score)二班总分 from AScore,AScoreZone where AScore.ClassNo=AScoreZone.ClassNo and ClassName='二班'group by ClassName)-
(select sum(Score)一班总分 from AScore,AScoreZone where AScore.ClassNo=AScoreZone.ClassNo and ClassName='一班'group by ClassName))
)'高出分数' from AScore,AScoreZone where AScore.ClassNo=AScoreZone.ClassNo group by CityZone