search
HomeBackend DevelopmentPHP Tutorialmysql一表连多表,多级关联能查询吗?

做php开发,遇到一个数据库处理问题:
现在要处理表inventory,这个表的一个字段goods_id.关联到表goods,但goods表里的多个字段又关连到其对应表;
这个表的另一个字段goods_level关联到表level。
不知道能否通过sql语句直接搞定,得到全部对应值?
如果不能通过sql语句搞定,要用什么方法来实现这个目的?请各位指点一二,谢!
还是上图好理解:


回复讨论(解决方案)

select * from inventory, goods, size, brand  where inventory.goods_id=goods.goods_id    and goods.goods_size=size.id    and goods.goods_brand=brand.id

只要找出表与表之间的关系,对应表关系,不是难事,关键是你sql基础牢不牢。

xuzuning兄,你没考虑到level表。

zy205817,我就是基础不牢,要不然哪会再这提问。如果你知道怎么解决,麻烦指点下,感激不尽

select * from inventory, goods, size, brand, level  where inventory.goods_id=goods.goods_id    and goods.goods_size=size.id    and goods.goods_brand=brand.id    and inventory.goods_level=level.id

zy205817兄,按你写的执行报错了,说:
#1054-
unknow column inventory.goods_levle in where clause

确定表inventory有这个字段goods_level

给你一个复杂点的...
给你解释一下...分成两部分,第一个是先组成一个临时表为c,这个表是查询你的goods表然后左连接到你的size表跟brand表.
然后查询你的inventory表再左连接上面的c表跟level表...

select a.id,a.supplier,a.warehouse_id,b.level,c.goods_name,c.size,c.brand from inventory as a left join level as b on a.goods_level = b.id left join (select a.goods_id as goods_id, a.goods_name as goods_name,b.brand as brand,c.size as size from goods as a left join brand as b on a.goods_brand=b.id left join size as c on a.goods_size=c.id) as c on a.goods_id=c.goods_id

谢谢leungigi的解答!解释很到位,一看就明白了,你一定是个良师益友!

顺路学习,感觉也很好。

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
PHP Dependency Injection Container: A Quick StartPHP Dependency Injection Container: A Quick StartMay 13, 2025 am 12:11 AM

APHPDependencyInjectionContainerisatoolthatmanagesclassdependencies,enhancingcodemodularity,testability,andmaintainability.Itactsasacentralhubforcreatingandinjectingdependencies,thusreducingtightcouplingandeasingunittesting.

Dependency Injection vs. Service Locator in PHPDependency Injection vs. Service Locator in PHPMay 13, 2025 am 12:10 AM

Select DependencyInjection (DI) for large applications, ServiceLocator is suitable for small projects or prototypes. 1) DI improves the testability and modularity of the code through constructor injection. 2) ServiceLocator obtains services through center registration, which is convenient but may lead to an increase in code coupling.

PHP performance optimization strategies.PHP performance optimization strategies.May 13, 2025 am 12:06 AM

PHPapplicationscanbeoptimizedforspeedandefficiencyby:1)enablingopcacheinphp.ini,2)usingpreparedstatementswithPDOfordatabasequeries,3)replacingloopswitharray_filterandarray_mapfordataprocessing,4)configuringNginxasareverseproxy,5)implementingcachingwi

PHP Email Validation: Ensuring Emails Are Sent CorrectlyPHP Email Validation: Ensuring Emails Are Sent CorrectlyMay 13, 2025 am 12:06 AM

PHPemailvalidationinvolvesthreesteps:1)Formatvalidationusingregularexpressionstochecktheemailformat;2)DNSvalidationtoensurethedomainhasavalidMXrecord;3)SMTPvalidation,themostthoroughmethod,whichchecksifthemailboxexistsbyconnectingtotheSMTPserver.Impl

How to make PHP applications fasterHow to make PHP applications fasterMay 12, 2025 am 12:12 AM

TomakePHPapplicationsfaster,followthesesteps:1)UseOpcodeCachinglikeOPcachetostoreprecompiledscriptbytecode.2)MinimizeDatabaseQueriesbyusingquerycachingandefficientindexing.3)LeveragePHP7 Featuresforbettercodeefficiency.4)ImplementCachingStrategiessuc

PHP Performance Optimization Checklist: Improve Speed NowPHP Performance Optimization Checklist: Improve Speed NowMay 12, 2025 am 12:07 AM

ToimprovePHPapplicationspeed,followthesesteps:1)EnableopcodecachingwithAPCutoreducescriptexecutiontime.2)ImplementdatabasequerycachingusingPDOtominimizedatabasehits.3)UseHTTP/2tomultiplexrequestsandreduceconnectionoverhead.4)Limitsessionusagebyclosin

PHP Dependency Injection: Improve Code TestabilityPHP Dependency Injection: Improve Code TestabilityMay 12, 2025 am 12:03 AM

Dependency injection (DI) significantly improves the testability of PHP code by explicitly transitive dependencies. 1) DI decoupling classes and specific implementations make testing and maintenance more flexible. 2) Among the three types, the constructor injects explicit expression dependencies to keep the state consistent. 3) Use DI containers to manage complex dependencies to improve code quality and development efficiency.

PHP Performance Optimization: Database Query OptimizationPHP Performance Optimization: Database Query OptimizationMay 12, 2025 am 12:02 AM

DatabasequeryoptimizationinPHPinvolvesseveralstrategiestoenhanceperformance.1)Selectonlynecessarycolumnstoreducedatatransfer.2)Useindexingtospeedupdataretrieval.3)Implementquerycachingtostoreresultsoffrequentqueries.4)Utilizepreparedstatementsforeffi

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 Article

Hot Tools

SecLists

SecLists

SecLists is the ultimate security tester's companion. It is a collection of various types of lists that are frequently used during security assessments, all in one place. SecLists helps make security testing more efficient and productive by conveniently providing all the lists a security tester might need. List types include usernames, passwords, URLs, fuzzing payloads, sensitive data patterns, web shells, and more. The tester can simply pull this repository onto a new test machine and he will have access to every type of list he needs.

SublimeText3 English version

SublimeText3 English version

Recommended: Win version, supports code prompts!

Safe Exam Browser

Safe Exam Browser

Safe Exam Browser is a secure browser environment for taking online exams securely. This software turns any computer into a secure workstation. It controls access to any utility and prevents students from using unauthorized resources.

Dreamweaver CS6

Dreamweaver CS6

Visual web development tools

Atom editor mac version download

Atom editor mac version download

The most popular open source editor