search
HomeDatabaseMysql TutorialSQL Server 表交叉显示及实现方法

假设有张学生成绩表(t)如下: Name Subject Result 张三 语文 73 张三 数学 83 张三 物理 93 李四 语文 74 李四 数学 84 李四 物理 94 想变成 姓名 语文 数学 物理 张三 73 83 93 李四 74 84 94 代码 create table #t ( Name varchar(10) , Subject varchar(

   假设有张学生成绩表(t)如下:

  Name Subject Result

  张三 语文  73

  张三 数学  83

  张三 物理  93

  李四 语文  74

  李四 数学  84

  李四 物理  94

  想变成

  姓名 语文 数学 物理

  张三 73  83  93

  李四 74  84  94

  代码

  create table #t

  (

  Name varchar(10) ,

  Subject varchar(10) ,

  Result int

  )

  insert into #t(Name , Subject , Result) values('张三','语文','73')

  insert into #t(Name , Subject , Result) values('张三','数学','83')

  insert into #t(Name , Subject , Result) values('张三','物理','93')

  insert into #t(Name , Subject , Result) values('李四','语文','74')

  insert into #t(Name , Subject , Result) values('李四','数学','83')

  insert into #t(Name , Subject , Result) values('李四','物理','93')

  declare @sql varchar(8000)

  set @sql = 'select Name as 姓名'

  select @sql = @sql + ' , sum(case Subject when ''' + Subject + ''' then Result end) [' + Subject + ']'

  from (select distinct Subject from #t) as a

  set @sql = @sql + ' from #t group by name'

  exec(@sql)

  drop table #t

  --结果

  姓名 数学 物理 语文

  ---------- ----------- ----------- -----------

  李四 83 93 74

  张三 83 93 73

  如果上述两表互相换一下:即

  姓名 语文 数学 物理

  张三 73  83  93

  李四 74  84  94

  想变成

  Name Subject Result

  张三 语文  73

  张三 数学  83

  张三 物理  93

  李四 语文  74

  李四 数学  84

  李四 物理  94

  代码

  create table #t

  (

  姓名 varchar(10) ,

  语文 int ,

  数学 int ,

  物理 int

  )

  insert into #t(姓名 , 语文 , 数学 , 物理) values('张三',73,83,93)

  insert into #t(姓名 , 语文 , 数学 , 物理) values('李四',74,84,94)

  select 姓名 as Name,'语文' as Subject,语文 as Result from #t union

  select 姓名 as Name,'数学' as Subject,数学 as Result from #t union

  select 姓名 as Name,'物理' as Subject,物理 as Result from #t

  order by 姓名 desc

  drop table #t

  Name Subject Result

  ---------- ------- -----------

  张三 数学 83

  张三 物理 93

  张三 语文 73

  李四 数学 84

  李四 物理 94

  李四 语文 74

  (所影响的行数为 6 行)

Statement
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
What are the differences in syntax between MySQL and other SQL dialects?What are the differences in syntax between MySQL and other SQL dialects?Apr 27, 2025 am 12:26 AM

MySQLdiffersfromotherSQLdialectsinsyntaxforLIMIT,auto-increment,stringcomparison,subqueries,andperformanceanalysis.1)MySQLusesLIMIT,whileSQLServerusesTOPandOracleusesROWNUM.2)MySQL'sAUTO_INCREMENTcontrastswithPostgreSQL'sSERIALandOracle'ssequenceandt

What is MySQL partitioning?What is MySQL partitioning?Apr 27, 2025 am 12:23 AM

MySQL partitioning improves performance and simplifies maintenance. 1) Divide large tables into small pieces by specific criteria (such as date ranges), 2) physically divide data into independent files, 3) MySQL can focus on related partitions when querying, 4) Query optimizer can skip unrelated partitions, 5) Choosing the right partition strategy and maintaining it regularly is key.

How do you grant and revoke privileges in MySQL?How do you grant and revoke privileges in MySQL?Apr 27, 2025 am 12:21 AM

How to grant and revoke permissions in MySQL? 1. Use the GRANT statement to grant permissions, such as GRANTALLPRIVILEGESONdatabase_name.TO'username'@'host'; 2. Use the REVOKE statement to revoke permissions, such as REVOKEALLPRIVILEGESONdatabase_name.FROM'username'@'host' to ensure timely communication of permission changes.

Explain the differences between InnoDB and MyISAM storage engines.Explain the differences between InnoDB and MyISAM storage engines.Apr 27, 2025 am 12:20 AM

InnoDB is suitable for applications that require transaction support and high concurrency, while MyISAM is suitable for applications that require more reads and less writes. 1.InnoDB supports transaction and bank-level locks, suitable for e-commerce and banking systems. 2.MyISAM provides fast read and indexing, suitable for blogging and content management systems.

What are the different types of JOINs in MySQL?What are the different types of JOINs in MySQL?Apr 27, 2025 am 12:13 AM

There are four main JOIN types in MySQL: INNERJOIN, LEFTJOIN, RIGHTJOIN and FULLOUTERJOIN. 1.INNERJOIN returns all rows in the two tables that meet the JOIN conditions. 2.LEFTJOIN returns all rows in the left table, even if there are no matching rows in the right table. 3. RIGHTJOIN is contrary to LEFTJOIN and returns all rows in the right table. 4.FULLOUTERJOIN returns all rows in the two tables that meet or do not meet JOIN conditions.

What are the different storage engines available in MySQL?What are the different storage engines available in MySQL?Apr 26, 2025 am 12:27 AM

MySQLoffersvariousstorageengines,eachsuitedfordifferentusecases:1)InnoDBisidealforapplicationsneedingACIDcomplianceandhighconcurrency,supportingtransactionsandforeignkeys.2)MyISAMisbestforread-heavyworkloads,lackingtransactionsupport.3)Memoryengineis

What are some common security vulnerabilities in MySQL?What are some common security vulnerabilities in MySQL?Apr 26, 2025 am 12:27 AM

Common security vulnerabilities in MySQL include SQL injection, weak passwords, improper permission configuration, and unupdated software. 1. SQL injection can be prevented by using preprocessing statements. 2. Weak passwords can be avoided by forcibly using strong password strategies. 3. Improper permission configuration can be resolved through regular review and adjustment of user permissions. 4. Unupdated software can be patched by regularly checking and updating the MySQL version.

How can you identify slow queries in MySQL?How can you identify slow queries in MySQL?Apr 26, 2025 am 12:15 AM

Identifying slow queries in MySQL can be achieved by enabling slow query logs and setting thresholds. 1. Enable slow query logs and set thresholds. 2. View and analyze slow query log files, and use tools such as mysqldumpslow or pt-query-digest for in-depth analysis. 3. Optimizing slow queries can be achieved through index optimization, query rewriting and avoiding the use of SELECT*.

See all articles

Hot AI Tools

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Undress AI Tool

Undress AI Tool

Undress images for free

Clothoff.io

Clothoff.io

AI clothes remover

Video Face Swap

Video Face Swap

Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Tools

Notepad++7.3.1

Notepad++7.3.1

Easy-to-use and free code editor

MantisBT

MantisBT

Mantis is an easy-to-deploy web-based defect tracking tool designed to aid in product defect tracking. It requires PHP, MySQL and a web server. Check out our demo and hosting services.

DVWA

DVWA

Damn Vulnerable Web App (DVWA) is a PHP/MySQL web application that is very vulnerable. Its main goals are to be an aid for security professionals to test their skills and tools in a legal environment, to help web developers better understand the process of securing web applications, and to help teachers/students teach/learn in a classroom environment Web application security. The goal of DVWA is to practice some of the most common web vulnerabilities through a simple and straightforward interface, with varying degrees of difficulty. Please note that this software

mPDF

mPDF

mPDF is a PHP library that can generate PDF files from UTF-8 encoded HTML. The original author, Ian Back, wrote mPDF to output PDF files "on the fly" from his website and handle different languages. It is slower than original scripts like HTML2FPDF and produces larger files when using Unicode fonts, but supports CSS styles etc. and has a lot of enhancements. Supports almost all languages, including RTL (Arabic and Hebrew) and CJK (Chinese, Japanese and Korean). Supports nested block-level elements (such as P, DIV),

ZendStudio 13.5.1 Mac

ZendStudio 13.5.1 Mac

Powerful PHP integrated development environment