Community
Articles
Topics
Q&A
Learn
Course
Programming Dictionary
Tools Library
Development tools
Website Source Code
PHP Libraries
JS special effects
Website Materials
Extension plug-ins
Leisure
Game Download
Game Tutorials
English
简体中文
English
繁体中文
日本語
한국어
Melayu
Français
Deutsch
Login
singup
关于LEFT JOIN 的主表和子表的问题
学习ing
2016-12-20 16:29:27
0
1
922
例如 A LEFT JOIN B 中A是主标还是字表
1
0
0
学习ing
reply all
(1)
I'll reply
Close
阿神
2016-12-20 16:29:46
1 floor
A是左表，B相当于子表，查询时A表全部内容都显示，B表中只会显示和A表中有交集的部分，B表不一定会全部显示
Like
+0
Add Reply
关闭回复
学习ing
reply
Popular Topics
More>
CakePHP Tutorial
Laravel Tutorial
PHP Tutorial
Java Tutorial
Popular Articles
How to download the Virtual Coin app on Apple mobile phone Summary of the Apple version of the Virtual Coin app
Ranking of digital currency software trading platform apps in the currency circle. Which of the top ten digital currency apps is better?
Stalker 2 Budmo mission guide: Should you steal from the stashes?
Sengoku Dynasty: How To Make Cooking Pot
How to take shelter from the Emission in Stalker 2
Popular Tutorials
More>
Related Tutorials
Popular Recommendations
Latest courses
The latest ThinkPHP 5.1 world premiere video tutorial (60 days to become a PHP expert online training course)
1421331
PHP introductory tutorial one: Learn PHP in one week
4265244
JAVA Beginner's Video Tutorial
2516771
The latest ThinkPHP 5.1 world premiere video tutorial (60 days to become a PHP expert online training course)
1421331
JAVA Beginner's Video Tutorial
2516771
Little Turtle's zero-based introduction to learning Python video tutorial
506275
Quick introduction to web front-end development
215630
Master PS video tutorials from scratch
886376
[Web front-end] Node.js quick start
7206
Complete collection of foreign web development full-stack courses
5609
Go language practical GraphQL
4722
550W fan master learns JavaScript from scratch step by step
673
Python master Mosh, a beginner with zero basic knowledge can get started in 6 hours
23778
Latest Downloads
More>
Web Effects
Website Source Code
Website Materials
Front End Template
[form button] jQuery enterprise message form contact code
[Player special effects] HTML5 MP3 music box playback effects
[Menu navigation] HTML5 cool particle animation navigation menu special effects
[form button] jQuery visual form drag and drop editing code
[Player special effects] VUE.JS imitation Kugou music player code
[html5 special effects] Classic html5 pushing box game
[Picture special effects] jQuery scrolling to add or reduce image effects
[Photo album effects] CSS3 personal album cover hover zoom effect
[Bootstrap template] Organic fruit and vegetable supplier web template Bootstrap5
[backend template] Bootstrap3 multifunctional data information background management responsive web page template-Novus
[Bootstrap template] Real estate resource service platform web page template Bootstrap5
[Bootstrap template] Simple resume information web template Bootstrap4
[Bootstrap template] bootstrap responsive widescreen book education website template-DREAMLIFE
[backend template] MAC style responsive blue enterprise CMS background management system template
[backend template] Responsive gradient atmosphere background management system website template-usinessbox
[Bootstrap template] Responsive vegetable and fruit store website template-Organio
[PNG material] Cute summer elements vector material (EPS PNG)
[PNG material] Four red 2023 graduation badges vector material (AI EPS PNG)
[banner picture] Singing bird and cart filled with flowers design spring banner vector material (AI EPS)
[PNG material] Golden graduation cap vector material (EPS PNG)
[PNG material] Black and white style mountain icon vector material (EPS PNG)
[PNG material] Superhero silhouette vector material (EPS PNG) with different color cloaks and different poses
[banner picture] Flat style Arbor Day banner vector material (AI+EPS)
[PNG material] Nine comic-style exploding chat bubbles vector material (EPS+PNG)
[Front-end template] Home Decor Cleaning and Repair Service Company Website Template
[Front-end template] Fresh color personal resume guide page template
[Front-end template] Designer Creative Job Resume Web Template
[Front-end template] Modern engineering construction company website template
[Front-end template] Responsive HTML5 template for educational service institutions
[Front-end template] Online e-book store mall website template
[Front-end template] IT technology solves Internet company website template
[Front-end template] Purple style foreign exchange trading service website template
![[Web front-end] Node.js quick start](https://img.php.cn/upload/course/000/000/067/662b5d34ba7c0227.png)
A是左表，B相当于子表，查询时A表全部内容都显示，B表中只会显示和A表中有交集的部分，B表不一定会全部显示