简体中文(ZH-CN) English(EN) 繁体中文(ZH-TW) 日本語(JA) 한국어(KO) Melayu(MS) Français(FR) Deutsch(DE)
Home > Backend Development > PHP Tutorial > body text

表连接与外键连接有什么区别？

WBOY
Release： 2016-06-06 20:42:19
Original
1658 people have browsed it

表连接与外键连接有什么区别？

回复内容：

表连接与外键连接有什么区别？

表连接是table join的query，执行sql的时候

外键是表间的存在的关系

表连接是多表查询时候,不同的表里有关系字段的连接,是你通过sql来控制的
外键是一种约束,是dbms管理的,如果一个表里的一个字段的外键是另一个表里的字段值,那么dbms会检查合法性

Related labels：
mysql php web Database Design
source：php.cn
Previous article：上传了一个.txt的文件 然后修改以后再上传 外链地址一样但是内容没改变 Next article：开启wamp中的gizp压缩的问题
Statement of this Website
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
Latest Articles by Author
Latest Issues
PHP arrays obtained from URL parameters do not behave as expected I have a URL parameter that contains the category ID and I want to treat it as an array li...
From 2024-04-06 22:09:02
0
1
1428
Where should I place CustomLog directive in apache I'm using php:7.2-apachedocker. I need to disable health check url login access log. Based...
From 2024-04-06 22:03:59
0
1
990
What is the format of the variables in the return value? I am a new learner of php. I found a piece of code: if($x<time()){return[false,'error']...
From 2024-04-06 21:55:20
0
1
778
Problems encountered when using opentbs to generate odt files: values ​​of the same key are displayed in the same row instead of separate columns. I'm using a library called OpenTbs to create odt using PHP, I'm using it because columns a...
From 2024-04-06 20:18:18
0
1
483
Group MySQL results by ID for looping over I have a table with flight data in mysql. I'm writing a php code that will group and displ...
From 2024-04-06 17:27:56
0
1
406
Related Topics
More>
Popular Recommendations
Popular Tutorials
More>
Related Tutorials
Popular Recommendations
Latest courses
Latest Downloads
More>
Web Effects
Website Source Code
Website Materials
Front End Template
About us Disclaimer Sitemap
php.cn：Public welfare online PHP training，Help PHP learners grow quickly！